The correct choice is
A. III and IV only
according to newton's second law, force is directly proportional to the acceleration of the object and vice versa and is given as
F = ma
where F = net force on the object
m = mass of the object
a = acceleration of the object
when an unbalanced force acts on an object, the object experiences acceleration. we know that acceleration is nothing but the time rate of change of velocity. hence object experience change in velocity. The velocity can change either by a change in speed or by change in direction of motion.