Assertion (A) : Frenkel defects are shown by `AgX`.
Reason (R ) : `Ag^(o+)` ions have small size.

Options

A. If both `(A)` and `(R)` are correct, and `(R)` is the correct explanation of `(A)`
B. If both `(A)` and `(R)` are correct, but `(R)` is not the correct explanation of `(A)`
C. If `(A)` is correct, but `(R)` is incorrect.
D. If both `(A)` is incorrect but `(R)` is correct.

Answer

To solve the question, we need to analyze the assertion and reason provided:

**Assertion (A):** Frenkel defects are shown by AgX.
**Reason (R):** Ag^(o+) ions have small size.

### Step-by-Step Solution:

1. **Understanding Frenkel Defects:**
- Frenkel defects occur when an ion is missing from its lattice position and occupies an interstitial site. This typically happens when there is a significant size difference between the cation and anion.

2. **Analyzing the Assertion:**
- The assertion states that Frenkel defects are shown by AgX. AgX refers to silver halides such as AgCl, AgBr, etc. These compounds indeed exhibit Frenkel defects due to the size difference between Ag^+ ions and the halide ions (Cl^-, Br^-, etc.).

3. **Analyzing the Reason:**
- The reason states that Ag^+ ions have a small size. This is true; Ag^+ ions are relatively small compared to the halide ions. The small size of the cation (Ag^+) compared to the larger halide ions (like Cl^-, Br^-) leads to the formation of Frenkel defects.

4. **Conclusion:**
- Both the assertion and reason are correct. Furthermore, the reason correctly explains why Frenkel defects occur in AgX. Therefore, the correct option is that both A and R are correct, and R is the correct explanation of A.

### Final Answer:
The correct option is **Option 1**: Both A and R are correct, and R is the correct explanation of A.