During cleavage, what is true about cells?

Options

A. Nucleocytoplasmic ratio remains unchanged
B. Size does not increase
C. There is less consumption of oxygen
D. The division is like meiosis

Explanation

### Step-by-Step Solution

1. **Understanding Cleavage**: Cleavage refers to the rapid mitotic cell division that occurs after fertilization, leading to the formation of a multicellular structure from a single-celled zygote.

2. **Identifying the Nature of Division**: Cleavage involves mitosis, not meiosis. Therefore, any statement suggesting that cleavage resembles meiosis is incorrect.

3. **Examining the Nucleus-Cytoplasm Ratio**: During cleavage, the nucleus-cytoplasm ratio actually increases, not remains unchanged. This is because the cells (blastomeres) divide without significant growth in cytoplasmic volume.

4. **Size of Cells**: As cleavage progresses, the size of the individual cells (blastomeres) decreases. However, the overall size of the embryo does not increase during this process, which is a key characteristic of cleavage.

5. **Oxygen Consumption**: The consumption of oxygen during cleavage is generally lower than in later stages of development, but this is not a defining characteristic of cleavage itself.

6. **Conclusion**: The statement that is true about cells during cleavage is that the size does not increase.

### Final Answer
During cleavage, the true statement about cells is: **Size does not increase.**

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