Final answer:
An object in dynamic equilibrium is one that is in motion but with a constant velocity. A cat sits on a bed without moving.
Step-by-step explanation:
An object in dynamic equilibrium is one that is in motion but with a constant velocity, meaning that its speed and direction remain unchanged.
The only option that describes an object in dynamic equilibrium from the given choices is A) A cat sits on a bed without moving. In this situation, the cat is stationary and not changing its position, indicating a constant velocity of zero.