Answer: Choice A
The -3 out front of that function means |-3| = 3 is the amplitude, which is the largest of the four functions.
In general, the sine function is
y = A*sin(B(x-C)) + D
where |A| is the amplitude. In the first answer choice, A = -3 so |A| = |-3| = 3.
Cosine has the same format since cosine is just a phase shift of sine.
