【单选题】

Mr.Black is going to London by train. When he gets to the station, there are too many people there. He can’t get on the tram. Just before the train starts, he has to jump into it through a window.

Unluckily, one of his shoes falls to the grounD、He can’t pick it up. Then he takes off the other one and throws it on the ground out of the train.A、little boy asks him in surprise, "Why do you do that " Mr.Black answers with a smile, "If a poor man picks them up, he may get a pair of shoes.\
Mr.Black got on the train by______.A．walking into it
B．jumping into it
C．flying into it