(A) : For long distance transmission of radio waves, short wave bands are used.
(R) : Short waves are reflected from ionosphere.

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 abd 'R' false
D. A' is false and 'R' is false

Answer

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

### Step-by-Step Solution:

1. **Understanding the Assertion (A)**:
- The assertion states: "For long distance transmission of radio waves, short wave bands are used."
- Short wave bands typically operate in the frequency range of 1.6 to 30 MHz. These frequencies are suitable for long-distance communication because they can travel beyond the horizon.

2. **Understanding the Reason (R)**:
- The reason states: "Short waves are reflected from the ionosphere."
- The ionosphere is a layer of the Earth's atmosphere that is ionized by solar and cosmic radiation. It can reflect certain radio waves, particularly short waves, back to the Earth, allowing them to travel long distances.

3. **Analyzing the Relationship**:
- The assertion is true because short wave bands are indeed used for long-distance radio communication.
- The reason is also true because short waves can be reflected by the ionosphere, which facilitates long-distance transmission.

4. **Conclusion**:
- Both the assertion (A) and the reason (R) are true.
- Additionally, the reason (R) correctly explains the assertion (A) because the reflection of short waves from the ionosphere is what enables long-distance communication.

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

---