Assuming no one moves..

Maybe D, definitely* C, potentially E.

* Also assuming the stone/boulder doesn't get stuck in D's position.

D can just duck, so he should be safe.

C should be dead regardless

A should die from not paying attention, be should survive from ducking

D.

The stone's circumference is 2pi. The distance to D's head is 2pi, so it makes one complete rotation.

The rolling stone is ~20% lighter than than stationary stone, so it won't tip the lever and spike C or launch the stationary stone.