[A]: In some organisms the end stages of the ancestral development pattern are dropped, as in case of neoteny.
[R]: In some animals, some middle stages are dropped in the descendents.

a. If both A and R are true and R is the correct explanation of A
b. If both A and R are true but R is not the correct explanation of A
c. If A is true and R is false
d. If both A and R are false

Options

A. If both A and R are true and R is the correct explanation of A
B. If both A and R are true but R is not the correct explanation of A
C. If A is true and R is false
D. If both A and R are false

Answer

To solve the question, we need to analyze both statements A and R and determine their truthfulness and the relationship between them.

### Step-by-Step Solution:

1. **Understanding Statement A**:
- Statement A mentions that in some organisms, the end stages of the ancestral development pattern are dropped, specifically referring to neoteny.
- Neoteny is a developmental phenomenon where the juvenile traits are retained in the adult form. This means that certain end stages of development are indeed omitted in some organisms.
- **Conclusion**: Statement A is true.

2. **Understanding Statement R**:
- Statement R states that in some animals, some middle stages are dropped in the descendants.
- This refers to a different aspect of developmental biology where certain intermediate forms may not appear in the descendants, which is also a recognized phenomenon.
- **Conclusion**: Statement R is true.

3. **Analyzing the Relationship Between A and R**:
- Although both statements A and R are true, they refer to different aspects of developmental changes.
- Statement A discusses the dropping of end stages (as in neoteny), while Statement R discusses the dropping of middle stages.
- Therefore, R does not explain A; they are related in the context of development but do not directly correlate as cause and effect.
- **Conclusion**: R is not the correct explanation of A.

4. **Final Conclusion**:
- Since both A and R are true but R does not explain A, the correct answer is option **b**: If both A and R are true but R is not the correct explanation of A.

### Summary of the Answer:
The correct answer is **b**: Both A and R are true but R is not the correct explanation of A.

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