Question

the number of cycles a wave completes per second.
frequency
period
transverse wave
longitudinal

Explanation:

To solve this, we analyze each option:

• "frequency" is defined as the number of cycles a wave completes per second.
• "period" is the time taken for one cycle, not the number of cycles per second.
• "transverse wave" refers to a wave type (oscillations perpendicular to direction), not the cycle count per second.
• "longitudinal" is also a wave type (oscillations parallel to direction), not related to cycles per second.

So the correct term matching the definition is "frequency".

Answer:

A. frequency (assuming the first option is labeled as A, with text "frequency")