In Drosophila the males have

Options

A. one X and one Y chromosome
B. a pair of X chromosomes
C. a pair of Y chromosomes
D. a pair of Z chromosomes

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about the chromosomal composition of male Drosophila (fruit flies).

2. **Identifying Chromosomes in Drosophila**: In Drosophila, the males have a specific set of sex chromosomes.

3. **Chromosomal Composition of Male Drosophila**: Male Drosophila have one X chromosome and one Y chromosome. This is similar to the sex determination system found in humans.

4. **Comparison with Female Drosophila**: To clarify, female Drosophila have two X chromosomes (XX), while males have one of each (XY).

5. **Evaluating the Options**:
- Option 1: One X and one Y chromosome - **Correct**.
- Option 2: A pair of X chromosomes - **Incorrect** (this is true for females).
- Option 3: A pair of Y chromosomes - **Incorrect** (males have one Y chromosome).
- Option 4: A pair of Z chromosomes - **Incorrect** (Z chromosomes do not exist in Drosophila).

6. **Conclusion**: The correct answer is that male Drosophila have one X and one Y chromosome.

### Final Answer:
In Drosophila, the males have **one X and one Y chromosome**.

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