To solve this problem, we need to identify which statement is not correct among the given options. Let's analyze each option:$\newline \bullet$Option 1: Retinal is the light-absorbing portion of visual photo pigments.$\newline$ - This statement is correct. Retinal is indeed the light-absorbing molecule in visual pigments.$\newline \bullet$Option 2: In retina, the rods have the photopigment rhodopsin while cones have three different photopigments.$\newline$ - This statement is correct. Rods contain rhodopsin, and cones have three types of photopigments for color vision.$\newline \bullet$Option 3: Retinal is a derivative of Vitamin C.$\newline$ - This statement is incorrect. Retinal is actually a derivative of Vitamin A, not Vitamin C.$\newline \bullet$Option 4: Rhodopsin is the purplish-red protein present in rods only.$\newline$ - This statement is correct. Rhodopsin is found in rods and is responsible for low-light vision.$\newline$Therefore, the statement that is not correct is Option 3.$\newline$The correct option is Option 3.