I believe it's B. Apologies if I'm wrong.
Answer: Option C.
Population density is the total number of organisms within a fixed area.
Explanation:
Population density is the total number of organisms per unit area. Population density is calculated by dividing the number of organisms by the unit area either in square kilometers, squaremeters, square miles.
Population density =number of organisms ÷ unit of land area.
Photosynthesis allows plants, algae and certain bacteria to turn sunlight into chemical energy. The amazing feat is achieved because sunlight can fuel a reaction between water and carbon dioxide that, in turn, produces carbohydrates (simple sugars) and oxygen.
Hope this helped