A man sitting in a train, facing the engine. He tosses a coin up, the coin falls behind him. Which of the following options is correct about the train?

As the coin is thrown in the vertical direction only, so due to inertia of motion, it cannot travel in the horizontal direction, and it will land in the position where it was thrown. But as the train is moving, the man has also moved forward. So, the train is accelerating in the forward direction.
If the train were at rest or moving backward, the coin would fall back into the man's hand or in front of him, respectively. The fact that the coin falls behind him suggests that the train is moving forward.