The problem is simple, a spring is between a wall and a block on a friction-less surface, what happens after the mass is released BUT before the spring reaches the relaxed position. I chose the velocity and the acceleration of the mass will continually decrease. The answer is F=-kx, acceleration is in the difection of motion, increasing velocity. since deltaX decreases the force will be smaller resulting in decreased acceleration. I'm calling BS on this question in general. It sounds like they chose (average) velocity and (instant) acceleration as the correct answer, leaving the other answers invalid. Since there are no stipulations on this matter, how is it that one is correct and the other not?