>>509273223
This.
Imagine the cube is two heavy masses held together by a thin string. The string breaks because one object is moving and the other one is not.
B cannot be the answer:
1. The blue portal must move somehow to reveal that the cube never moved.
2. The piston pushing on orange portal must feel resistance because the blue portal can't move out of the way.
3. But now angular momentum kicks our ass because it's incompatible with the suggested kinematic model.
You can't break physics, portals are impossible okay gang?