Answer: -a (4th choice)
Explanation:
Consider an example like y = 2(x-3)^2 and compare it to y = -2(x-3)^2
The jump from a = 2 to a = -2 means we reflect over the x axis. This is because we're effectively multiplying the y coordinate values by -1. So a point like (5,8) moves to (5,-8).
