Answer: A. 20 seconds
Step-by-step explanation:
We know that if a function has a repeating pattern then it is called a periodic function (like sine or cosine).
The period is the length of the smallest interval that contains exactly one copy of the repeating pattern. It is the horizontal distance required for the graph of a periodic function to complete one cycle.
From the graph it can be seen that, the horizontal distance required for the graph of a periodic function= 20 .
Therefore, it takes 20 seconds by Callie to complete one full swing.
