The photic zone or euphotic zone is the depth of the water in a lake or ocean, that is exposed to such intensity of light at which the rate of oxygen consumption, is equal to the rate of carbon dioxide production. It extends from the surface down to a depth where light intensity falls to one percent of that at the surface, called the euphotic depth. About 90% of all marine life lives in the euphotic zone.

Benthos are the organisms found at the bottom of freshwater bodies such as lakes, rivers, and streams and since light cannot reach such deep water, therefore, they depend upon organic matter. This dead and decaying matter sustain their food chain hence, they are mostly scavengers or detritivores, belonging to primary consumers of detritus food chain.

Ponds and lakes are stationary fresh water ecosystems. Ponds are generally shallower with depth less than 2 meters. Shallow lakes are eutrophic with rich biota and quick circulation of nutrients. Producers in a pond or lake ecosystem include phytoplanktons like diatoms, desmids, Chlorella, Chlamydomonas, Spirogyra, Chlamydomonas, Oedogonium etc. Littoral zones occur on the edge of large lakes and rivers, having dense growth of vegetation. Therefore, the correct answer is option B.

1) The zone at the edge of a lake or sea or in an aquatic habitat which is alternatively exposed to air is called 'Littoral zone'.

Littoral zone is the shallow coastal zone. Light is available upto bottom in this zone. Therefore, producers are found throughout from surface to bottom in this zone. Rooted vegetation occurs along shores. Consumers are also available throughout, i.e., from surface to the bottom in this zone.

The abyssal zone is the abyssopelagic layer or pelagic zone, that contains the very deep benthic communities near the bottom of oceans. The benthic zone begins from shore to continental shelf. The deep sea floor is called as the abyssal plain.

Benthos is the community of organisms that live in or near the seabed. This zone is called as the benthic zone. Chronomid larvae, phantom larva, clams, red annelids are some organisms that belongs to benthose of a lake.