Answer:
A) Increase the height at point A.
Explanation:
As we know that Kinetic Energy (1/2 mv^2) of a body is also dependent on it's potential energy and vice versa. So, when the roller coaster is moving, increasing the height at initial point will increase the Potential Energy (P.E = mgh) of the roller coaster and when it leaves the point A, it has more velocity and as we can guess from the equation eventually more Kinetic Energy.