Royal Botanical Garden is located in Kew, England.

• An arboretum is a botanical garden with trees. 
• Commonly a modern arboretum is a botanical garden containing living collections of woody plants and is intended for scientific study.
• So, the correct answer is 'Botanical garden with trees'

Nation Botanical Institute is located in Lucknow. It is engaged in the field of taxonomy and modern biology. Initially engaged in research work in the classical botanical disciplines, the National Botanical Institute went on laying an increasing emphasis in keeping with the national needs and priorities in the field of plant sciences, on its applied and developmental research activities. 

• Botanical gardens or greenhouses are the place where rare plants can be taken care of outside its natural habitat. Botanical gardens play important role in plant conservation and protection. These are the center for ex situ conservation. 

Botanical garden of the forest research institute was established in 1906 at Dehradun. It is a premier institution in the field of forestry research in India.Here, botanical research is carried out under disciplines Systematic Botany, Plant Physiology and Wood Anatomy.

Originally conceptualized and set up as the National Botanic Gardens (NBG) by Professor Kailas Nath Kaul on behalf of the State Government of Uttar Pradesh, it was taken over by the CSIR in 1953. Dr. Triloki Nath Khoshoo joined in 1964 as the Assistant Director, shortly afterward becoming the Director. Initially engaged in research work in the classical botanical disciplines, the NBG went on laying an increasing emphasis in keeping with the national needs and priorities in the field of plant sciences, on its applied and developmental research activities. Due to the untiring efforts of Dr. Khoshoo, the institute rose to the stature of being the National Botanical Research Institute in 1978, reflecting the correct nature and extent of its aims and objectives, functions and R & D activities. Sikandar Bagh is a famous and historic pleasure garden, located in the grounds of the Institute. The National Botanical Research Institute (NBRI) is a research institute of CSIR in Lucknow. It is engaged in the field of taxonomy and modern biology.

ICBN, "International Code of Botanical Nomenclature”, is the collection of rules of scientific nomenclature of plants and was first proposed by Sprague, Hitchcock, Green (1930) but was accepted in 1961. During 12$^{th}$ International congress, Leningrade 1975, ICBN was revised. The revised form was republished in 1978. Thus, ICBN was first revised in 1975. 

The botanical garden is an area where cultivation of a wide variety of plants is done for the purpose of research and education. The rare and endangered plant species can also be conserved in this areas. The plants in the botanical gardens can be cultured for educational as well as research purposes. 

There are various kinds of tourist attractions in Lucknow. They have museums, monuments, tombs and many other attractive sites to visit. But the one that provides most refreshing and enriching experience on Lucknow Tour are the well laid out gardens in Lucknow. However among all the gardens, the Botanical Gardens in Lucknow draw huge attention.

ICBN, "International Code of Botanical Nomenclature”, is the collection of rules of scientific nomenclature of plants and was first proposed by Sprague, Hitchcock, Green (1930) but was accepted in 1961. During 12th International congress, Leningrade 1975, ICBN was revised. The revised form was republished in 1978. Thus, ICBN was proposed in 1930. Thus, the correct answer is option A.

• A botanical garden or botanic garden is a garden dedicated to the collection, cultivation, preservation, and display of a wide range of plants labelled with their botanical names or It is an establishment where plants are grown for scientific study and display to the public.
• There are now estimated to be 1775 botanic gardens in 148 countries around the world with many more under construction.
  
•  Kew Royal Gardens in London, England has the world's largest collection of living plants.
  
• The number of species growing in botanical gardens worldwide is about 80,000.
  
• So,the correct answer is '80,000'.

Botanical gardens are sufficiently large sized tracts where plants belonging to different types and localities are grown for scientific and educational purposes. Botanical gardens mainly serve the purpose of providing ex-situ conservation(conservation of selected rare plants/animals in places outside their natural homes) of endangered plant species.

Botanical gardens help in
(i) Providing plant material for comparative taxonomic studies.
(ii) Functioning as acclimatisation centres for exotic plants of economic importance.
(iii) Growing and maintaining records of local flora.
(iv) Providing seeds and living materials for different research work.
(v) Growing and maintaining and endangered plants.