Answer:
Period
Step-by-step explanation:
As we know that the time period of a given cycle means the the time to complete one revolution or one vibration
Here we know that one vibration or one oscillation means to and fro motion of an object will complete when it crosses the mean position in both the directions and comes to its initial position
In this type of to and fro motion one complete vibration is completed in one Time period and number of vibrations per second is known as frequency of the vibration
So here correct answer will be
A). Period