A : Spy satilight cameras use lenses with very large aperatures.
R : In general, larger the aperture in an optical instrument, the greater the resolution.

Options

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

Answer

To solve the question, we need to analyze the assertion (A) and the reason (R) provided:

**Assertion (A):** Spy satellite cameras use lenses with very large apertures.
**Reason (R):** In general, larger the aperture in an optical instrument, the greater the resolution.

### Step-by-Step Solution:

1. **Understanding the Assertion (A):**
- Spy satellite cameras are designed to capture high-resolution images from great distances. To achieve this, they require lenses that can gather as much light as possible, which is facilitated by having a large aperture. This allows the camera to function effectively in various lighting conditions and capture finer details.

2. **Understanding the Reason (R):**
- The reason states that larger apertures lead to greater resolution. This is a fundamental principle in optics. The resolution of an optical instrument is its ability to distinguish between two closely spaced objects. A larger aperture allows more light to enter the lens, which improves the resolving power of the instrument.

3. **Linking Assertion and Reason:**
- The assertion (A) about spy satellite cameras using large apertures is directly supported by the reason (R). The reason explains why large apertures are advantageous in optical instruments, including spy cameras, by stating that they enhance resolution.

4. **Conclusion:**
- Since both the assertion and the reason are true, and the reason provides a correct explanation for the assertion, we conclude that the correct answer is: **Both A and R are true, R is the correct explanation of A.**

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

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