The correct answer is - B. Forest floor.
The forest floor in the rainforests has everything that the animals need for survival. Food, water, nicer temperature, lots of biomass, prey... Because of this, lots of animals are living mostly on the forest floor and doing their activities. Also, the largest animals are not well suited for life on the branches because of their weight, and also some species of animals just do not have the required ''equipment'' (claws, long strong tails for balance, rotational limbs and toes) for life in the canopies, so they prefer the floor.