Which theory states that the principle cause of forgetting is passage of time? A. motivated forgetting B. retrieval failure C. decay theory D. ineffective encoding

Decay's theory explains that memory, by the mere passage of time, fades. As time passes the information is less available for later retrieval. So that the information is not lost over time it is necessary to rehearse it.

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.