I say its B, because if we jump in a portal we fly out of the other one. Now the difference is here the portal is moving and not the person, but in physics we are only interested in the motion of two bodys relative to each other. If you are standing on the train you would see the portal as stationary and the people coming towards it. Because the object/person enters the portal with speed it also comes out with the same speed.

Jerboa fande ich auch mäßig. Seitdem ich aber Sync und Infinity nutze, fühlt sich die Seite wieder sehr viel mehr polished an und so wie früher Reddit.

Well Im a rat. Nice