Assertion :- Factors occurs in pairs in an organism.
Reaosn :- In a dissimilar pair of facrtors one member of the pair dominates the other.

Options

A. If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion.
B. If both Assertion & Reason are trur but Reason is not a correct explanation of the Assertion.
C. If Assertion is True but the Reason is Flase.
D. If both Assertion & Reason are false.

Answer

### Step-by-Step Solution:

1. **Understanding the Assertion**: The assertion states that "Factors occur in pairs in an organism." In genetics, these factors refer to alleles, which are different forms of a gene. According to Mendelian genetics, alleles for a trait are inherited in pairs, one from each parent.

2. **Understanding the Reason**: The reason provided is "In a dissimilar pair of factors, one member of the pair dominates the other." This refers to the concept of dominance, where in a heterozygous condition (e.g., one dominant allele and one recessive allele), the dominant allele masks the expression of the recessive allele.

3. **Evaluating the Truth of the Assertion**: The assertion is true because alleles indeed occur in pairs. For example, in the case of a trait controlled by a single gene, an organism will possess two alleles for that gene, one inherited from each parent.

4. **Evaluating the Truth of the Reason**: The reason is also true. In a pair of alleles, if one is dominant and the other is recessive, the dominant allele will express itself in the phenotype, while the recessive allele will not.

5. **Assessing the Relationship Between Assertion and Reason**: Although both the assertion and the reason are true, the reason does not correctly explain the assertion. The assertion is about the pairing of factors (alleles), while the reason discusses the dominance relationship between different alleles.

6. **Conclusion**: Based on the evaluation, the correct option is that both the assertion and reason are true, but the reason is not the correct explanation of the assertion.

### Final Answer:
Both the assertion and reason are true, but the reason is not the correct explanation of the assertion.

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