A person has defective blue colour appreciation. His condition is better named as-
**Core Concept**
Blue colour appreciation is mediated by the long-wavelength cones in the retina, which are sensitive to blue light. Defective blue colour appreciation is a type of colour vision deficiency, also known as colour blindness.
**Why the Correct Answer is Right**
Defective blue colour appreciation is typically caused by a mutation in the OPA1 gene, which encodes a protein involved in the development and maintenance of the retina. This mutation leads to a reduction in the number or function of the long-wavelength cones, resulting in impaired blue colour vision. The condition is often inherited in an X-linked recessive pattern, meaning it is more common in males.
**Why Each Wrong Option is Incorrect**
* **Option A:** Red colour appreciation is mediated by the middle-wavelength cones, which are sensitive to red light. Defective red colour appreciation is not the correct answer.
* **Option B:** Green colour appreciation is mediated by the middle-wavelength cones, which are sensitive to green light. However, defective green colour appreciation is not the primary condition being described.
* **Option C:** This option is not provided, but it is likely a distractor.
**Clinical Pearl / High-Yield Fact**
Colour vision deficiency is a common condition affecting approximately 8% of males and 0.5% of females worldwide. It can have significant implications for certain professions, such as aviation and the military, where colour vision is essential for safety and performance.
**Correct Answer:** C.