Give the number of chromosomes in Drosophila melanogaster.

Explanation

**Step-by-Step Solution:**

1. **Identify the Organism**: The organism in question is Drosophila melanogaster, commonly known as the fruit fly.

2. **Understand Chromosome Number**: In genetics, the total number of chromosomes is often represented as 2n, where n is the number of homologous pairs.

3. **Determine the Value of n**: For Drosophila melanogaster, it is known that there are 4 homologous pairs of chromosomes. Therefore, n = 4.

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