1. The problem statement, all variables and given/known data 2. Relevant equations 3. The attempt at a solution My answer is a because for ball B it loses kinetic energy when it drops into the dip and comes back up. I'm having a hard time picturing ball b when it goes down the dip.. does it drop down and then jumps up back on the track? or unless it is stuck onto the track the whole time and slows down when it climbs back up onto the track after the dip?