Researchers who have studied color blindness and color deficiency have found that a total color blindness is extremely rare in animal species. b total color blindness in humans usually occurs when cones of the retina are absent or malfunctional. c blue-yellow color blindness is the most common form of color deficiency. d color deficiency is more frequently found in women than in men.

Option-B

Explanation:

Color deficiency is a condition caused when the person is not able to distinguish the different colors. Since the person is not able to distinguish different color, therefore, the chromo-receptors which are affected are the cone cells located in the retina which allows us to see different wavelengths.

1. Total color blindness is not a rare disease in animals.

2. Total color blindness in which a person is not able to see any color occurs when all types of cone cells become malfunction or completely absent.

3. The red-green color blindness is more common than the blue-yellow color blindness.

4. The mother is usually not affected as she is the carrier of the gene responsible for the color blindness.

Since all options except Option-2 are incorrect therefore option-2 is the correct answer.