Answer
b. No
Explanation:
We can easily solve this question by using a graphing calculator or any plotting tool, to check if it is a sinusoid.
The function is
f(x) = sin(20*x) + cos(8*x)
Which can be seen in the picture below
We can notice that f(x) is a not sinusoid. It has periodic amplitudes, and the function has a period T = π/2
The maximum and minimum values are
Max = 1.834
Min = -2