Gene mutation is caused :-

Options

A. Due to reproduction
B. Due to linkage
C. Due to change in sequence of `N_(2)` base
D. Due to changes in sequence of genes in DNA

Answer

### Step-by-Step Solution:

1. **Understanding Gene Mutation**:
- Gene mutation refers to a permanent change in the DNA sequence that constitutes a gene. This alteration can lead to variations in traits among individuals.

2. **Identifying Causes of Mutation**:
- The question presents several options regarding what causes gene mutations. The options include:
- A) Due to reproduction
- B) Due to linkage
- C) Due to change in sequence of nitrogenous bases
- D) Due to change in sequence of genes and DNA

3. **Evaluating Each Option**:
- **Option A: Due to reproduction**: This is incorrect as reproduction itself does not directly cause mutations.
- **Option B: Due to linkage**: Linkage refers to the tendency of genes located close together on a chromosome to be inherited together. This does not cause mutations.
- **Option C: Due to change in sequence of nitrogenous bases**: This is correct. Mutations occur when there is a change in the sequence of nitrogenous bases (adenine, thymine, cytosine, guanine) in the DNA.
- **Option D: Due to change in sequence of genes and DNA**: While this sounds plausible, it is too broad. Mutations specifically refer to changes at the level of the nitrogenous bases.

4. **Conclusion**:
- The correct answer to the question "Gene mutation is caused:" is **C) due to change in sequence of nitrogenous bases**.