Mutation is

Options

A. Achange in phenotype of an organism caused by some environmental factor
B. An inheritable change in genetic material
C. A temporary change in structure of the nucleus
D. Any one of the above

Answer

**Step-by-Step Solution:**

1. **Definition of Mutation**:
- Mutation refers to a change in the base sequences of genes. This alteration can occur in various ways and can be caused by different agents.

2. **Causes of Mutation**:
- Mutations can be induced by mutagens, which are agents that cause mutations. These mutagens can be classified into three main categories:
- **Physical Mutagens**: These include radiation such as gamma rays and X-rays.
- **Chemical Mutagens**: These are various chemicals that can alter DNA sequences.
- **Biological Mutagens**: These include biological agents such as certain viruses that can integrate into the host's genetic material.

3. **Understanding the Options**:
- The question provides several options regarding the definition of mutation.
- **Option 1** states that mutation is a change in the phenotype caused by environmental factors. This is incorrect as mutations specifically refer to genetic changes, not just phenotypic changes.
- **Option 2** states that mutation is a genetic change that is inheritable. This is the correct definition of mutation.
- **Option 3** claims that mutation is a temporary change in the structure of the nucleus. This is also incorrect as mutations are permanent changes in the DNA sequence.

4. **Conclusion**:
- Based on the definitions and the analysis of the options, the correct answer is that mutation is a genetic change in the base sequences of genes, which can be inherited and can lead to phenotypic changes.

**Final Answer**: Mutation is a change in the base sequences of genes caused by mutagens, and the correct option is option number 2.

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