Identify the graph of the equation over the given interval.

y=3sin (2x-pi/2)

x is greater than or equal to -pi/4 and x is less than or equal to 3pi/2.

I think I found the period to be: pi

the amplitude is 3.

the phase shift is pi as well?

I'm unsure as to what to do after this though.

My choices are these, but I don't know how to determine which is correct. I'm not just looking for an easy answer, I really want to try to understand this. Thanks so much guys.