Complete linkage is observed in:

Options

A. Male Drosophilla sp.
B. Female Drosophilla sp.
C. Female silkworm
D. None of these

Answer

**Step-by-Step Solution:**

1. **Understanding Linkage**: Linkage refers to the tendency of genes that are located close to each other on the same chromosome to be inherited together. When two alleles are closely situated, they are less likely to be separated during meiosis.

2. **Definition of Complete Linkage**: Complete linkage occurs when two alleles are so close together on a chromosome that they are almost always inherited together, resulting in a recombination frequency of less than 50%. This means that the alleles do not assort independently.

3. **Example of Complete Linkage**: A classic example of complete linkage is observed in the fruit fly, Drosophila melanogaster. In male Drosophila, certain traits such as eye color (red eyes) and wing type (normal wings) are often inherited together due to their close proximity on the same chromosome.

4. **Observation in Male Drosophila**: In male Drosophila, the traits for red eyes and normal wings are linked. This means that when these flies reproduce, the offspring are likely to inherit these traits together, demonstrating complete linkage.

5. **Conclusion**: Therefore, complete linkage is primarily observed in male Drosophila, where specific traits are consistently passed down together from one generation to the next.

**Final Answer**: Complete linkage is observed in male Drosophila.

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