What is true for photolithotrophs?

Options

A. Obtain energy from radiations and `H_2` from organic compounds.
B. Obtain energy from radiations and `H_2` from inorganic compounds.
C. Obtain energy from organic compounds
D. Obtain `H_2` from organic compounds

Answer

To determine what is true for photolithotrophs, we need to analyze their characteristics based on the definitions of the terms involved.

### Step-by-Step Solution:

1. **Understanding Photolithotrophs**:
- Photolithotrophs are a type of bacteria that utilize light as their energy source (photo) and inorganic compounds as their source of electrons or hydrogen (litho).

2. **Breaking Down the Options**:
- **Option A**: "Obtain energy from radiations and hydrogen from organic compounds."
- This statement is incorrect because photolithotrophs obtain hydrogen from inorganic compounds, not organic compounds.

- **Option B**: "Obtain energy from radiations and hydrogen from inorganic compounds."
- This statement is correct. Photolithotrophs do indeed obtain energy from light (radiation) and hydrogen from inorganic sources.

- **Option C**: "Obtain energy from organic compounds."
- This statement is incorrect because photolithotrophs do not obtain energy from organic compounds; they use light as their energy source.

- **Option D**: "Obtain hydrogen from organic compounds."
- This statement is also incorrect because photolithotrophs obtain hydrogen from inorganic compounds.

3. **Conclusion**:
- The only true statement regarding photolithotrophs is **Option B**: "Obtain energy from radiations and hydrogen from inorganic compounds."

### Final Answer:
- The correct answer is **Option B**.