The superhero "nighthawk" has excellent night vision but poor vision in the daytime. one reason for "nighthawk’s" ability is due to a large number of
1) kryptonite2) photoreceptors3) rods4) cones

3). Rods.

Explanation:

As per the question, NightHawk's ability to have an outstanding vision at night while deficient during daytime is due to 'large number of rods' in his eye as these rods(being exclusively responsible for night vision) enable them to see at night due to being relatively more sensitive than the cones. NightHawk's day vision is poor as these rods are almost insensitive to color and they(rods) help in 'peripheral or indirect vision' not the 'central or direct vision'. Thus, option 3 is the correct answer.