T(rule)y Problem - Sopuli

I think it has to be A. You figure that if it were B, the people on the track would suddenly be traveling at a high velocity, but the train’s velocity wouldn’t be impacted at all, since there was no impact between the train and the people. Wouldn’t this mean that the portal had created energy, which is impossible?
Portals already break the laws of physics. The virtual world inside the orange portal is moving at the same velocity as the trolley, think about how much kinetic energy that is
I don’t think the portal contains anything within itself, though. The portal is a non-entity - it’s just that if you pass through the portal, you suddenly find yourself in a different location, as if that location were right next to you. The portal itself has no other properties of its own, I’d think.