Two first graders (Mike and Tim) are on opposite ends of a seesaw. Why does Mike not go flying off his end of the seesaw when Tim pushes down on the other end? Tim is not applying enough force to move Mike's mass that much.
Tim is not applying enough force to move Mike's mass that much.

The strength of Tim's force is not as great as the force of gravity pushing Mike down.
The strength of Tim's force is not as great as the force of gravity pushing Mike down.

Mike is sitting on the fulcrum, which is attached to the board and doesn't move.
Mike is sitting on the fulcrum, which is attached to the board and doesn't move.

both A and B
both A and B