Caro's acid is

Options

A. `H_2SO_5`
B. `H_2S_2O_8`
C. `H_2SO_3`
D. `H_2S_2O_3`

Explanation

To determine which compound is Caro's acid, we need to analyze the given options: H2SO5, H2SO8, H2SO3, and H2S2O3.

### Step-by-Step Solution:

1. **Identify the Name of Caro's Acid**:
- Caro's acid is known as peroxy monosulfuric acid.

2. **Check the Chemical Formula**:
- The chemical formula for peroxy monosulfuric acid is H2SO5.

3. **Analyze the Other Options**:
- **H2SO8**: This is known as peroxodisulfuric acid.
- **H2SO3**: This is sulfurous acid.
- **H2S2O3**: This is thiosulfuric acid.

4. **Conclusion**:
- Among the options given, H2SO5 is the only one that corresponds to Caro's acid.

5. **Final Answer**:
- Therefore, the correct answer is H2SO5.