A child has a single kidney since birth. This variation is

Options

A. positive meristic
B. negative meristic
C. substantive
D. blastogenic

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question states that a child has a single kidney since birth and asks us to classify this variation.

2. **Identifying the Types of Variations**: We have four options to choose from:
- Positive meristic
- Negative meristic
- Substantive
- Blastogenic

3. **Defining the Terms**:
- **Positive Meristic Variation**: This refers to an increase in the number of structures (e.g., more digits, more leaves).
- **Negative Meristic Variation**: This refers to a decrease in the number of structures (e.g., fewer digits, fewer organs).
- **Substantive Variation**: This generally refers to variations that do not fit into meristic categories; they are more about qualitative differences.
- **Blastogenic Variation**: This refers to variations that occur due to changes in the germ cells or during the development of the organism.

4. **Analyzing the Situation**: Since the child has a single kidney, this indicates a decrease in the number of kidneys, which aligns with the definition of negative meristic variation.

5. **Conclusion**: The correct classification of the variation where a child has a single kidney since birth is **negative meristic variation**.

6. **Final Answer**: Therefore, the correct answer is option 2: **negative meristic**.

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