The correct option is (a).
Explanation
The human eye functions as an optical instrument where the retina acts as the light-sensitive screen. The retina contains two primary types of photoreceptor cells-rods and cones-which convert light energy into electrical signals sent to the brain via the optic nerve.
Statement-wise Analysis
- Statement 1 is Correct: Cones are photoreceptor cells responsible for photopic vision (daylight vision). They are less sensitive to light than rods and require bright light to function effectively. They enable high visual acuity and color perception.
- Statement 2 is Incorrect: Rods are responsible for scotopic vision (twilight or dim light vision). They are highly sensitive to light and allow vision in low-light conditions. They do not function in bright light due to the saturation of their pigment, rhodopsin.
- Statement 3 is Incorrect: Rods are not capable of distinguishing colors; they provide monochromatic (black and white) vision. Color sensing is the specific function of cones, which exist in three types sensitive to different wavelengths (red, green, and blue).
Key Takeaway
Rods are essential for vision in dim light (night vision) and do not detect color. Cones are essential for vision in bright light and are responsible for color differentiation.