Assertion : Comparative biochemistry provides a strong evidence in favour of common ancestry of living beings.
Reason : Genetic code is universal.

Options

A. (a) If both A and R are true and R is the correct explanation of A
B. (b) If both A and R are true but R is not the correct explanation of A
C. (c) If A is true and R is false
D. (d) If both A and R are false

Answer

### Step-by-Step Solution:

1. **Understanding the Assertion**: The assertion states that "Comparative biochemistry provides a strong evidence in favour of common ancestry of living beings." This means that by studying the biochemical processes and components (like proteins and enzymes) across different organisms, we can find similarities that suggest a shared evolutionary history.

2. **Exploring Comparative Biochemistry**: Comparative biochemistry involves analyzing the biochemical substances (like proteins and enzymes) that are present in various organisms. For example, cytochrome c is a protein involved in the electron transport chain, which is crucial for ATP production in cells.

3. **Example of Cytochrome c**: The similarity of cytochrome c sequences among different organisms (like humans, mice, and horses) indicates that these species are closely related. This similarity in biochemical components supports the idea of common ancestry, as it suggests that these organisms have evolved from a common ancestor.

4. **Understanding the Reason**: The reason provided states that "Genetic code is universal." This means that the way genetic information is translated into proteins is consistent across all forms of life. For instance, the codon AUG always codes for the amino acid methionine, regardless of the organism.

5. **Linking Assertion and Reason**: Both the assertion and reason are true. The assertion is about the evidence of common ancestry derived from comparative biochemistry, while the reason highlights the universality of the genetic code. However, the universality of the genetic code does not directly explain why comparative biochemistry provides evidence for common ancestry.

6. **Conclusion**: Since both statements are true but the reason does not directly explain the assertion, the correct answer is that both the assertion and reason are true, but the reason is not the correct explanation for the assertion. Therefore, the answer is option B.