A red blood cell placed in 50% NaCl solution will :

Options

A. undergo crenation
B. swell and eventually burst due to water intake
C. stay the same size
D. none of the above

Explanation

To solve the question regarding what happens to a red blood cell (RBC) when placed in a 50% NaCl solution, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Environment**:
- A 50% NaCl solution is a highly concentrated saline solution. In biological terms, this is considered a hypertonic solution compared to the internal environment of the red blood cell.

2. **Osmosis Concept**:
- Osmosis is the movement of water across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration.

3. **Effect on Red Blood Cell**:
- When an RBC is placed in a hypertonic solution (like 50% NaCl), water inside the RBC will move out into the surrounding solution to balance the solute concentrations.

4. **Resulting Changes in the RBC**:
- As water leaves the RBC, it will begin to shrink or crenate. This process is known as crenation, where the cell loses water and shrivels up.

5. **Conclusion**:
- Therefore, the correct answer to the question is that the red blood cell will undergo crenation when placed in a 50% NaCl solution.

### Final Answer:
A red blood cell placed in a 50% NaCl solution will undergo crenation.

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