Assertion: For law of independent assortment, two pairs of contrasting characters are used simultaneously in a cross.
Reason: It is a dihybrid cross.

Options

A. If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
B. If both Assertion and Reason are true and the Reason is not the correct explanation of the Assertion.
C. If Assertion is true but the Reason is false.
D. If both Assertion and Reason are false.

Answer

**Step-by-Step Solution:**

1. **Understanding the Assertion:**
- The assertion states that for the law of independent assortment, two pairs of contrasting characters are used simultaneously in a cross. This is true because the law of independent assortment applies when examining two different traits at the same time.

2. **Understanding the Reason:**
- The reason provided states that this is a dihybrid cross. A dihybrid cross involves two traits, each represented by two alleles. While it is true that a dihybrid cross is used to demonstrate the law of independent assortment, the assertion does not specifically require it to be a dihybrid cross.

3. **Evaluating the Law of Independent Assortment:**
- The law of independent assortment, proposed by Gregor Mendel, states that alleles for different traits segregate independently of one another during gamete formation. This means that the inheritance of one trait will not affect the inheritance of another trait.

4. **Conclusion:**
- The assertion is correct because it accurately describes the application of the law of independent assortment. However, the reason is incorrect because it implies that the law can only be demonstrated through a dihybrid cross, which is not the case. Therefore, the assertion is true, while the reason is false.

**Final Answer:**
- The assertion is correct, and the reason is incorrect.

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