Assertion : Genetic variation shown by the plant Rauwolfia vomitoria growing in different Himalayan ranges is very important economically.
Reason : The amount and variety of alkaloids presents in this plant, change both between the Rauwolfia species and between the different strains of R. vomitoria.

Options

A. a) If both assertion and reason are true and reason is the correct explanation of assertion.
B. b) If both assertion and reason are true but reason is not the correct explanation of assertion.
C. c) If assertion is true but reason is false.
D. d) If both assertion and reason are false.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Assertion**: The assertion states that genetic variation in the plant Rauwolfia vomitoria, which grows in different Himalayan ranges, is economically important. This suggests that the differences in genetic makeup can lead to variations that may have significant economic implications.

2. **Identifying the Economic Importance**: Rauwolfia vomitoria is known for producing an important alkaloid called reserpine. This compound is utilized in the synthesis of various drugs, indicating that the plant has substantial economic value due to its medicinal properties.

3. **Analyzing the Reason**: The reason provided states that the amount and variety of alkaloids present in Rauwolfia vomitoria change between different species and strains. This implies that genetic variation among the plants can lead to differences in the concentration and types of alkaloids produced.

4. **Connecting Assertion and Reason**: The assertion and reason are interconnected. The genetic variation (assertion) leads to differences in alkaloid production (reason), which is crucial for the economic value of the plant. Therefore, the reason supports the assertion.

5. **Evaluating the Options**: Based on the analysis:
- Option A states that both the assertion and reason are true, and the reason is the correct explanation for the assertion. This is accurate.
- Other options suggest either one of the statements is false or that the reason does not explain the assertion, which is incorrect.

6. **Conclusion**: The correct answer is Option A, as both the assertion and reason are true, and the reason correctly explains the assertion.