Answer
Ball B's speed is the greatest at maximum height, then A, and C is the slowest.
Work Step by Step
At maximum height, the y-component of all the balls' velocities are zero. This means that only the x-component must be analyzed. Based off the graph, we see that ball B traveled the furthest, then A, and then C. Logically, the further the ball goes, the faster it was traveling (in this situation). So, the greatest speeds of the ball are directly correlated with their ranges; Ball B> Ball A> Ball C.