I think the answer is b.boom
I believe the answer is D
The answer would be A, as B refers to conduction and C and D refer to radiation. Convection is the transfer of different temperature currents, i.e, A
This would be typical of an elastic collision.
Relative motion means a motion relative to a reference point. We can also say, relative motion means motion referred or observed from a reference point.
For example, Alex is in a train and Ace is at the station, when the train starts moving, for Ace it is moving at a speed of 10 m/s, but for Alex it is moving at 0 m/s, or we can say that it is at rest for Alex, but in motion for Ace. This is relative motion.