Impulse-momentum theorem Steps:

• Initial momentum of ball: $2 \times 4 = 8$ kg m/s (towards wall).
• Final momentum of ball: $2 \times (-2) = -4$ kg m/s (away from wall).
• Change in momentum: $-4 - 8 = -12$ kg m/s.
• Average force on wall: magnitude of $\Delta p / \Delta t = 12 / 0.15 = 80$ N (action-reaction pair).

Why D is correct:

• It matches the impulse-momentum theorem, where impulse on wall equals magnitude of ball's momentum change divided by collision time.

Why the others are wrong:

• A ignores momentum change, underestimating force.
• B uses incorrect partial velocity difference, like $(4-2) \times 2 / 0.15 \approx 27$ N adjusted wrongly.
• C assumes ball stops ($\Delta p = 8$ kg m/s), giving $8 / 0.15 \approx 53$ N, forgetting rebound adds to change.

Final answer: D