Amy gets up from her seat on a train to move closer to the front. just as she begins to walk forward, the train stops at a station. what is the best explanation of what happens to amy?

a. while amy is walking, her body is in motion. when the train stops, because she's not buckled in, amy continues to move forward due to inertia.

b. while amy is walking, her body is in motion. when the train stops, an unbalanced force accelerates her body backward.

c. while amy is walking, her body is in motion, but as the train stops, it exerts a force on amy opposite to the direction she is walking, causing her to stop as well.

d. while amy is walking, she is in motion due to the force of repulsion. when the train stops, she is catapulted forward due to the train's stronger force of attraction.

my best guesses would be d or c, but only from what common sense tells me. answer and explanation, ? guys!