Answer: C+2
Reason:
The largest sin(x) can get is 1, and the same goes for sin(3x).
Consequently, the largest 2sin(3x) can get is 2.
You can visually verify these claims by graphing each function with a tool like Desmos. Take note of the y coordinate of the highest points. See below.
Therefore, the largest f(x) = 2sin(3x)+C can get is 2+C or C+2
