In prophase, chromosomes shorten and thicken due to

Options

A. microtubules
B. coiling of chromosomes
C. disappearance of microfilament
D. formation of proteins

Answer

### Step-by-Step Solution:

1. **Understanding Prophase**: Prophase is the first stage of cell division in both mitosis and meiosis. During this phase, several key changes occur in the cell.

2. **Chromatin Structure**: Chromatin is a complex of DNA and proteins found in the nucleus of eukaryotic cells. It exists in a less condensed form during interphase but undergoes significant changes during prophase.

3. **Condensation of Chromatin**: During prophase, the chromatin condenses. This means that the chromatin fibers become more tightly packed, resulting in the formation of visible chromosomes.

4. **Coiling of Chromatin**: The process of condensation involves the coiling of the chromatin strands. This coiling is what causes the chromosomes to become shorter and thicker.

5. **Conclusion**: The shortening and thickening of chromosomes during prophase is primarily due to the coiling of chromatin. Therefore, the correct answer to the question is option **B: Coiling of chromosome**.