[A]: Disorders like scrapie in sheeps and goats are caused by Prions.
[R]: The build up of prion occurs in the brain causing neuro degenerative disorders.

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

### Step-by-Step Solution:

1. **Understanding the Assertion**: The assertion states that disorders like scrapie in sheep and goats are caused by prions.
- **Explanation**: Scrapie is indeed a fatal neurodegenerative disease that affects sheep and goats, and it is caused by prions, which are misfolded proteins that can induce other proteins to misfold.

2. **Understanding the Reason**: The reason provided is that the buildup of prions occurs in the brain, causing neurodegenerative disorders.
- **Explanation**: Prions accumulate in the brain and lead to the degeneration of neural tissue, which is characteristic of neurodegenerative diseases. This buildup disrupts normal brain function and leads to the symptoms associated with diseases like scrapie.

3. **Evaluating the Truth of the Statements**: Both the assertion and the reason are true.
- **Assertion**: True, because scrapie is caused by prions.
- **Reason**: True, because the accumulation of prions in the brain leads to neurodegenerative disorders.

4. **Determining the Relationship**: The reason is a correct explanation of the assertion.
- **Explanation**: The reason explains how prions cause the disorder mentioned in the assertion by detailing the mechanism (buildup in the brain leading to neurodegeneration).

5. **Conclusion**: Since both the assertion and the reason are true, and the reason correctly explains the assertion, the final answer is that both statements are true and the reason is the correct explanation for the assertion.

### Final Answer:
Both [A] and [R] are true, and [R] is the correct explanation of [A].

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