Hydrogen nucleus combines to form helium then energy is released.
Binding energy/nucleon of `He` is greater than hydrogen.

Options

A. If both A and R are true and R is the correct explanation of A.
B. If both A and R are true but R is not the correct explanation of A.
C. If A is true but R is false
D. If A is false but R is true.

Explanation

To solve the question, we need to analyze the assertion and the reason provided in the statement.

### Step-by-step Solution:

1. **Understanding the Assertion**:
- The assertion states that hydrogen nuclei combine to form helium and that energy is released in the process. This is a reference to nuclear fusion, which occurs in stars, including our sun.
- In the fusion process, hydrogen isotopes (like deuterium and tritium) can combine to form helium. The reaction can be simplified as:
\[ 2 \, ^1H + 2 \, ^1H \rightarrow \, ^4He + 24.9 \, \text{MeV} \]
- This indicates that when two hydrogen nuclei fuse, they release energy (24.9 MeV).

2. **Understanding the Reason**:
- The reason states that the binding energy per nucleon of helium is greater than that of hydrogen.
- Binding energy per nucleon is a measure of the stability of a nucleus. A higher binding energy per nucleon indicates a more stable nucleus.
- Helium, being a heavier nucleus with two protons and two neutrons, has a higher binding energy per nucleon compared to hydrogen, which consists of a single proton.

3. **Evaluating the Truth of the Statements**:
- Both the assertion and the reason are true.
- The assertion is true because energy is indeed released when hydrogen nuclei fuse to form helium.
- The reason is also true because helium has a higher binding energy per nucleon than hydrogen, which explains why energy is released during the fusion process.

4. **Conclusion**:
- Since both the assertion and the reason are true, and the reason correctly explains the assertion, we conclude that the correct answer is:
- Both A and R are true, and R is the correct explanation of A.

### Final Answer:
Both A and R are true, and R is the correct explanation of A.