1. The problem statement, all variables and given/known data 2. Relevant equations 3. The attempt at a solution I chose D because I thought that since it is at the lowest point on the wave, it will move upwards with the greatest speed. But I'm wrong, since the answer is C. Is the answer C because of some time of acceleration from point D to C? If so, then why is the answer not B instead? Or the water waves here can be compared to the swinging pendulum, where velocity is greatest at its equilibrium position. I have no trouble understanding the pendulum case but I can't picture the velocity of the water waves at their different positions.