Which of the following correctly shows a pair of homologous chromosomes at the start of meiosis?

Options

A.
B.
C.
D.

Answer

To determine which option correctly shows a pair of homologous chromosomes at the start of meiosis, we need to understand the characteristics of homologous chromosomes.

### Step-by-Step Solution:

1. **Definition of Homologous Chromosomes**:
Homologous chromosomes are pairs of chromosomes that are similar in shape, size, and carry the same genes at the same loci. However, the alleles (versions of the genes) may differ between the two chromosomes.

2. **Characteristics to Identify**:
When identifying homologous chromosomes, look for:
- Similar length and shape.
- Same gene loci.
- One chromosome from each parent.

3. **Analyzing the Options**:
- **Option A**: Check if the chromosomes are similar in size and shape. If one chromosome is significantly longer or shorter than the other, this option is incorrect.
- **Option B**: Again, compare the lengths and shapes of the chromosomes. If they have different arm lengths or shapes, this option is also incorrect.
- **Option C**: Look for any differences in size or shape. If they do not match, this option is incorrect as well.
- **Option D**: This option should show two chromosomes that are identical in size and shape. If they match in these aspects, this is the correct option.

4. **Conclusion**:
After analyzing all the options, the correct answer is the one where the chromosomes are identical in size and shape, indicating they are homologous.

### Final Answer:
The correct option that shows a pair of homologous chromosomes at the start of meiosis is **Option D**.

---