What happens to the inertia of an object when its velocity is doubled?
A) the object's inertia becomes ?2 times greater.
B) the object's inertia becomes 2 times greater.
C) the object's inertia becomes 4 times greater
D) the object's inertia is unchanged

THE OBJECTS INERTIA BECOMES 2 TIMES GREATER = 2mv [formula for double inertia]

The inertia remains unchanged because as we know that inersia is the measure of mass  and since mass is not changing so inertia niether changes.

The only thing that increases is the momentum. because from equation we know p=mv that is momentum is the product of mass and velocity and since velocity is increasing so so momentum increases automatically.