Question

in the context of the passage, the word waves can be understood as
a a movement of water and a fleeting emotion.
b a greeting and a signal.
c a pattern and a disturbance.
d a motion and a thought.

Explanation:

Without the passage context, we can consider common - sense interpretations of "waves". A wave can be a physical movement (like a greeting wave of the hand) which is a form of signal. It can also refer to a physical wave in water which can be seen as a signal in some contexts (e.g., ocean waves indicating weather changes).

Answer:

B. A greeting and a signal.