Alex and Kaylee Are Placed at the Two Ends of a Boat

Multiple Choice

Alex and Kaylee are placed at the two ends of a boat on a still lake. Alex, of mass 80 kg, decides to swap seats with Kaylee, of mass 60 kg. As a result, the boat will

A) move in the same direction Kaylee moves.
B) move in the same direction Alex moves.
C) move in the same direction Alex moves, then move in the same direction Kaylee moves; but its net displacement is zero.
D) move in the same direction Kaylee moves, then move in the same direction Alex moves; but its net displacement is zero.
E) not move at all.