A red blood cell was kept in a solution for a few where it got burst. The solution taken was:

Options

A. Hypotonic
B. Concentrated sugar solution.
C. Isotonic
D. Hypertonic.

Answer

To determine which solution caused the red blood cell to burst, we need to understand the concepts of osmosis and the types of solutions: hypotonic, hypertonic, and isotonic.

### Step-by-Step Solution:

1. **Understanding Osmosis**: Osmosis is the movement of water across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration. This process continues until equilibrium is reached.

2. **Types of Solutions**:
- **Hypotonic Solution**: A solution that has a lower concentration of solute compared to the inside of the cell. This means it has a higher concentration of water.
- **Isotonic Solution**: A solution that has the same concentration of solute as the inside of the cell. There is no net movement of water.
- **Hypertonic Solution**: A solution that has a higher concentration of solute compared to the inside of the cell. This means it has a lower concentration of water.

3. **Effect of Hypotonic Solution on Red Blood Cells**:
- When a red blood cell is placed in a hypotonic solution, water moves into the cell by osmosis because the concentration of solute is lower outside the cell.
- As water enters the cell, the cell swells due to the influx of water.

4. **Outcome of Swelling**:
- If the influx of water continues, the red blood cell will eventually swell to the point where it cannot contain the excess water, leading to the cell bursting (lysis).

5. **Conclusion**: Since the red blood cell was kept in a solution where it burst, the solution must have been hypotonic. Therefore, the correct answer is:
- **A. Hypotonic solution**.