Colour blindness in which all colours appear grey is

Options

A. Monochromatism
B. Dichromatism
C. Protanopia
D. Deuteranopia

Answer

**Step-by-Step Solution:**

1. **Understanding Color Blindness**: Color blindness is a condition where individuals have difficulty distinguishing between certain colors or see colors differently than those with normal vision.

2. **Identifying the Types of Color Blindness**:
- **Monochromatism**: This is a condition where a person cannot perceive any color at all, seeing only shades of gray, black, and white. This occurs due to a total lack of functioning cone cells in the retina.
- **Dichromatism**: This condition allows for the perception of only two colors out of the three fundamental colors (red, green, blue) due to the absence of one type of cone pigment.
- **Protanopia**: A specific type of dichromatism where the individual is unable to perceive red light due to the absence of red cones.
- **Deuteranopia**: Another type of dichromatism where the individual cannot perceive green light due to the absence of green cones.

3. **Analyzing the Question**: The question specifically asks for the type of color blindness where all colors appear gray.

4. **Conclusion**: Based on the definitions, monochromatism is the only type where individuals perceive everything in shades of gray. Therefore, the answer to the question is **monochromatism**.

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