Part B: Choose the best explanation from among the following: - Truck has more mass, and hence the force exerted on it it greater - The massive truck exerts a greater force on the lightweight car - Action-reaction forces always have equal magnitude

Solution
The answer would be "Equal to"
These forces from an action-reaction pair, and hence the force experienced by the car has the same magnitude as the force experienced by the truck.
For part B, the answer would be:
Action-reaction forces always have equal magnitude.