Question

the ______ is the time it takes for a wave to complete one cycle. trough period frequency hertz

Explanation:

• A trough is the lowest point of a wave.
• Frequency is the number of cycles per second (unit is hertz).
• Hertz is the unit of frequency.
• Period is defined as the time taken for a wave to complete one cycle. So the word that fits the blank is "period".

Answer:

B. period