Hello!
In trigonometric functions, the amplitude of a trigonometric function is the maximum displacement on the graph of that function. In the case of the sine and cosine functions, this value is the leading coefficient of the function.
If y = A sin x, then the amplitude is |A|.
Amplitude is like the height of a trigonometric function. And in this case, the amplitude of this function 3, and the height is 3.
Therefore, the maximum value is positive 3, and the minimum value is negative 3, so the function that has a maximum y-value of 3 is choice A, y = 3sin(x).
