A nice caption is:
Beach days and bonfire nights
Answer:
Galaxies move in a random pattern.
A laser is worked by electromagnetic radiation. The term "laser" originated as an acronym for "light amplification by stimulated emission of radiation".
The answer is
A, or convert an energy input to mechanical energy output.
This is because engines transfer whatever energy they need at first into mechanical energy to move. Like car engines. They make mechanical energy to help the car move.