Which of the following is an example of an 'action-at-a-distance' (non-contact) force?

The tendency of an object to resist a change in its state of motion is called:

A box of mass 15 kg is kept on the floor of a stationary trolley. The coefficient of static friction between the box and the trolley is 0.12. To keep the box stationary relative to the trolley, the maximum horizontal acceleration (in m/s2) with which the trolley can move is: (g = 10 m/s2)