Which of the following is the graph of f(x) = 3 sin (

The general form of a function with a trigonometric sine is y=Asin(Bx+C)+D where A is the amplitude and B is the frequency. From f(x) = 3 sin (2x),   A is equal to 3 which tells us that the graph has waves that has height from -3 to 3. B equals to 2 tells us that there are two waves between 0 and 2π.The period of the function then is π. The graph goes through the (0,0) point.