Ultimate source of organic variation is `:`

Options

A. Mutation
B. Sexual reproducing
C. Natural selection
D. Hormonal action

Answer

**Step-by-Step Solution:**

1. **Understanding Organic Variation**: Organic variation refers to the differences that occur among organisms. This can include differences in physical traits, behaviors, and genetic makeup.

2. **Identifying the Source of Variation**: The question asks for the ultimate source of this organic variation. To determine this, we need to consider what causes these differences in organisms.

3. **Role of Evolution**: Evolution is a slow and continuous process that results from variations. It is important to note that evolution is irreversible; once a change occurs, it cannot be undone.

4. **Common Ancestors and Interrelation**: Variations can arise due to the interrelation of organisms that share a common ancestor. This common ancestry leads to shared traits and resources among organisms.

5. **Understanding Mutation**: The ultimate source of organic variation is mutation. A mutation occurs when there is a change or damage to a DNA gene, altering the genetic message carried by that gene.

6. **Significance of Mutation**: Mutations are crucial because they can be passed from one generation to the next, leading to the development of new species over time. Other factors like natural selection and hormonal actions do not serve as the ultimate source of organic variation.

7. **Conclusion**: Therefore, the ultimate source of organic variation is mutation.

**Final Answer**: The ultimate source of organic variation is mutation.

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