An unbalanced force can cause an object to: check all that apply. a. change the direction of its velocity. b. change the magnitude of its velocity. c. remain motionless. d. remain moving with its current speed and direction.

The correct options are:
A. change the direction of its velocity.
B. change the magnitude of its velocity.

For instance, A is true in case of a uniform circular motion: if there is an unbalanced force that acts as centripetal force, this force changes the direction of the velocity of the object (it makes it turning in a circular path) but not its magnitude.

Instead, B is true for instance when an unbalanced force F is applied in the same direction of motion of the object: the object will experience an acceleration given by F=ma, and so since the object accelerates, the magnitude of its velocity will change.