The least constancy of shape is exhibited by ..............

Options

A. white blood cells
B. blood platelets
C. epithelial cells
D. red blood cells

Answer

To solve the question regarding which type of cell exhibits the least constancy of shape, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Options**: The question provides four types of cells: white blood cells (WBC), blood platelets, epithelial cells, and red blood cells. We need to analyze each type to determine which has the least consistent shape.

2. **Analyze White Blood Cells (WBC)**:
- WBCs, particularly lymphocytes and phagocytes, are known for their ability to change shape. They can stretch and form pseudopodia (false feet) to engulf foreign particles like bacteria and viruses.
- This ability to change shape allows them to move through tissues and respond to infections effectively.

3. **Consider Blood Platelets**:
- Blood platelets are small cell fragments that play a crucial role in blood clotting. They have a relatively consistent disc shape but can change slightly when activated to form clots.
- However, their shape is not as variable as that of WBCs.

4. **Examine Epithelial Cells**:
- Epithelial cells have a more defined shape based on their function and location (cuboidal, columnar, squamous). They maintain a consistent structure to form protective layers in tissues.
- Therefore, they do not exhibit the least constancy of shape.

5. **Look at Red Blood Cells**:
- Red blood cells (RBCs) have a biconcave disc shape that is consistent and is crucial for their function in transporting oxygen. They do not change shape significantly.

6. **Conclusion**:
- Among the options, white blood cells (WBCs) exhibit the least constancy of shape due to their amoeboid movement and ability to change form to engulf pathogens. Therefore, the correct answer is **white blood cells**.

### Final Answer:
The least constancy of shape is exhibited by **white blood cells (WBC)**.