Answer:
A. Change the direction of its velocity
B. Change the magnitude of its velocity
Step-by-step explanation:
When unbalanced force is applied on a system of mass then as per Newton's II law we can say
F = ma
so we have

so here the system of mass will move with a given acceleration
We can define this acceleration as rate of change in velocity according to which we can say that it is either change in magnitude of speed or it is change in the direction of the speed
So correct answer would be
A. Change the direction of its velocity
B. Change the magnitude of its velocity