Answer:
The correct option is 2.
Step-by-step explanation:
From the given graph it is clear that the maximum value of the function is 1 at x=0, therefore the required function is a cosine function.
The general form of a cosine function is
.... (1)
Where, a is amplitude, 2π/b is period, c is phase shift and d is vertical shift.

from the given graph it clear that the period of the function is
.


Phase shift is zero, i.e., c=0, because it is maximum at x=0. vertical shift is zero, i.e.,d=0 because midline is x-axis.
Substitute a=1, b=4, c=0, d=0 in equation (1).


Therefore the correct option is 2.