Assertion (A): The frequency of red-green colour blindness is many times higher in females than that in males.
Reason ( R): In females if only one X-chromosome of female possess allele for colour blind character she becomes the carrier.

Options

A. Both assertion (A) and reason ( R) are true and reason ( R) is the correct explanation of assertion (A).
B. Both assertion (A) and reason ( R) are true but reason ( R) is not the correct explanation of assertion (A).
C. Assertion (A) is true but reason ( R) is false.
D. Assertion (A) is false but reason ( R) is true.

Explanation

### Step-by-Step Solution:

1. **Understanding the Assertion (A)**:
- The assertion states that the frequency of red-green color blindness is many times higher in females than in males.
- This implies that more females are affected by color blindness compared to males.

2. **Understanding the Reason (R)**:
- The reason states that in females, if only one X-chromosome carries the allele for color blindness, the female becomes a carrier.
- This means that the female will not show symptoms of color blindness unless both X-chromosomes are affected.

3. **Analyzing the Genetic Basis**:
- Red-green color blindness is an X-linked recessive disorder.
- Males have one X and one Y chromosome (XY), while females have two X chromosomes (XX).

4. **Effects in Males**:
- Since males have only one X chromosome, if that X chromosome carries the allele for color blindness, the male will express the condition.
- Therefore, all males with the affected X chromosome will be color blind.

5. **Effects in Females**:
- Females have two X chromosomes. If one X chromosome carries the allele for color blindness and the other does not, the female will not be color blind but will be a carrier.
- A female will only be color blind if both of her X chromosomes carry the allele for color blindness.

6. **Conclusion**:
- Since males are affected if their single X chromosome carries the mutation, the frequency of color blindness is higher in males than in females.
- Therefore, the assertion (A) is incorrect, while the reason (R) is correct.

### Final Answer:
- Assertion (A) is false.
- Reason (R) is true.