The ultimate source of variations is

Options

A. (a) natural selection
B. (b) sexual reproduction
C. (c) mutation
D. (d) hormonal action

Explanation

**Step-by-Step Solution:**

1. **Understanding Variations**: Variations refer to the differences in traits among individuals within a species. These differences can be genetic, phenotypic, or environmental.

2. **Genetic Variations**: Genetic variations are the differences in gene frequencies within a population. They are crucial for the diversity of traits, such as skin color or hair color, among individuals of the same species.

3. **Importance of Genetic Variations**: Genetic variations are essential for the survival of species in changing environments. They provide the raw material for evolution and are the basis for natural selection, where the best-suited traits are favored.

4. **Evaluating Options**:
- **Option A - Natural Selection**: This is a process that acts on variations but is not a source of variations itself.
- **Option B - Sexual Reproduction**: While sexual reproduction introduces genetic diversity through the combination of gametes, it is not the ultimate source of variations.
- **Option C - Mutation**: Mutations are changes in the genetic sequence and can occur spontaneously. They are heritable and can be beneficial, neutral, or deleterious. Mutations are considered the ultimate source of genetic variations.

5. **Conclusion**: Based on the evaluation of the options, the ultimate source of variations is **mutation**.

**Final Answer**: The ultimate source of variations is **mutation**.

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