Dentin is a calcified tissue of the body. It is covered by enamel on the crown and cemented on the rod and surrounds the entire pulp.

 Skin tissues have highest rate of regeneration as it undergoes wear and tear on regular basis.

The vermiform appendix is attached dorsomedially to the end of the cecum.

Blue coloured eyes have relatively little melanin compared to brown eyes. People with no melanin many have light blue or pinkish eyes from reflection of light.

The small intestine in an adult human is about 7 metres (23 feet) long.

The large intestine is about 1.5 m long, which is about one-fifth of the length of the intestinal canal.

Option (1) is correct.

Melatonin produce acid in the pineal gland in forefather sleep, bright light inhibited by the melatonin, which is why our natural rhythm makes us wake up in morning and go to sleep at night.