Match each electromagnetic-radiation source in List-I with its physical source mechanism in List-II.

List 1

1. (A) Source of microwave frequency

2. (B) Source of infrared frequency

3. (C) Source of gamma rays

4. (D) Source of X-rays

5. .

6. .

List 2

1. (P) Radioactive decay of nucleus

2. (Q) Magnetron

3. (R) Inner-shell electrons

4. (S) Vibrations of atoms and molecules

5. (T) LASER

6. (U) RC circuit