What is true for celeavage ?

Options

A. Size of embryo increase
B. Size of cells decrease
C. Size of cells increase
D. Size of embryo decrease

Answer

### Step-by-Step Solution:

1. **Understanding Cleavage**: Cleavage is the process that occurs after fertilization, where the zygote undergoes a series of rapid cell divisions without growth. This process leads to the formation of smaller cells called blastomeres.

2. **Zygote Formation**: After fertilization, a diploid zygote is formed. This zygote is the starting point for cleavage.

3. **Cell Division**: During cleavage, the zygote divides into two cells (2-celled stage), then into four cells (4-celled stage), and continues to divide further (8-celled stage, 16-celled stage, etc.).

4. **Size of Cells**: As cleavage progresses, the size of the individual cells (blastomeres) decreases. This is because the total volume of the zygote is divided among an increasing number of cells, leading to smaller cell sizes.

5. **Size of Embryo**: The overall size of the embryo does not change during cleavage. The embryo remains the same size as the zygote until later stages of development when growth occurs.

6. **Evaluating Options**:
- Size of embryo increases: **False** (the size remains constant during cleavage).
- Size of cells decreases: **True** (as explained, the cells become smaller).
- Size of cells increases: **False** (the cells are getting smaller, not larger).
- Size of embryo decreases: **False** (the size remains the same).

7. **Conclusion**: The correct statement regarding cleavage is that the size of cells decreases.

### Final Answer:
The true statement for cleavage is that the size of cells decreases.