A : The possibility of a female becoming a haemophilic is extremely rare.
R : Mother of such a female has to be carrier and father should be haemophilio.

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1)
B. If both Assertion & Reason are true and the reason is not the correct explanation of the assertion , then mark (2)
C. If Assertion is true statement but Reason is false, then mark (3)
D. If both Assertion and Reason are false statements, then mark (4)

Answer

To solve the question regarding the assertion and reason about hemophilia in females, we can break it down into clear steps:

### Step-by-Step Solution:

1. **Understanding Hemophilia**:
- Hemophilia is an X-linked recessive disorder. This means that the gene responsible for hemophilia is located on the X chromosome.

2. **Female Genotype for Hemophilia**:
- Females have two X chromosomes (XX). For a female to be hemophilic, she must inherit the defective allele (denoted as H) on both of her X chromosomes. Therefore, her genotype would be X^H X^H (where X^H represents the X chromosome with the hemophilia allele).

3. **Carrier Females**:
- If a female has one normal X chromosome and one defective X chromosome, her genotype would be X^H X. In this case, she is a carrier of hemophilia but does not exhibit the disease.

4. **Normal Females**:
- A female with two normal X chromosomes (XX) will not have hemophilia and is not a carrier.

5. **Condition for a Female to be Hemophilic**:
- For a female to be hemophilic, she must inherit the defective allele from both parents. This means her mother must be a carrier (X^H X) or affected (X^H X^H), and her father must be hemophilic (X^H Y).

6. **Analyzing the Assertion**:
- The assertion states that the possibility of a female becoming hemophilic is extremely rare. This is true because it requires both X chromosomes to carry the defective allele, which is less likely compared to males who only need one defective allele (since they have only one X chromosome).

7. **Analyzing the Reason**:
- The reason states that the mother of such a female has to be a carrier and the father should be hemophilic. This is also true, as explained above. The mother must provide one defective allele (as a carrier) and the father provides the other defective allele (being hemophilic).

8. **Conclusion**:
- Both the assertion and reason are true, and the reason correctly explains the assertion. Therefore, the correct option is that both statements are true and the reason is the correct explanation of the assertion.

### Final Answer:
Both the assertion and reason are true, and the reason is the correct explanation of the assertion.

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