Does he though if the rolling boulder is lighter than the static boulder and a horizontal force is being applied to the seesaw instead of a vertical force?
Discussion
We don't have any way of knowing that from the evidence given.
True. Does that mean we can't definitively say that C dies either?
If we only assume 3 things; that E is pushing the Boulder, each boulder is made out of the same material based on its shading, nobody can move;
A won't get touched.
B will be trapt.
C will be severely injured or die
D will live due to the gap in the moving Boulder.
E will live because he pushed it.