In mammalian eye, the 'fovea' is the center of the visual field where

The fovea centralis is a small, central pit composed of closely packed cones in the eye. It is located in the center of macula lutea of the retina. It is responsible for sharp central vision which is required during driving and reading. This region has a high density of cones but rods are absent. The central fovea consists of very compact cones, thinner and more rod-like in appearance than cones found elsewhere. Since the fovea does not have rods, it is not sensitive to dim lights. So, the correct answer is option A.