Which of these is a fusion reaction ?

Options

A. `""^(3)H_(1)+""^(2)H_(1)to ""^(3)He_(1)+""^(1)""N_(0)`
B. `""^(238)U_(92)+""^(206)Pb_(82)+8(""^(4)He_(2))+6(""^(0)B_(1))`
C. `""^(12)C_(7)to ""^(12)C_(6)+beta+gamma`
D. none of the above

Explanation

To determine which of the given options represents a fusion reaction, we need to understand the definition and characteristics of fusion reactions.

### Step-by-Step Solution:

1. **Understand Fusion Reaction**:
- A fusion reaction is a nuclear reaction in which two lighter atomic nuclei combine to form a heavier nucleus. This process releases a significant amount of energy.

2. **Identify the Characteristics**:
- In a fusion reaction, the reactants are lighter nuclei (e.g., isotopes of hydrogen like deuterium and tritium).
- The product is a heavier nucleus (e.g., helium).

3. **Analyze the Options**:
- Look at the options provided (though not listed here, we assume there are multiple choices).
- Identify which option describes the combination of two lighter nuclei to form a heavier nucleus.

4. **Select the Correct Option**:
- Based on the definition, if one of the options states that two lighter nuclei combine to form a heavier nucleus, that option is the correct answer.

5. **Conclusion**:
- The correct option is the one that describes the fusion of two lighter nuclei into a heavier nucleus.

### Final Answer:
- The correct option is **A**, which states that two lighter nuclei combine to form a heavier nucleus.