Answer :
Box A has 2x the mass of Box B so Box A has more inertia as compared to Box B.
Relationship between inertia and mass
More the mass of an object, there is more inertia of the body. Thus, if mass of two bodies is same their inertia will also be same. Hence, inertia of A and B will be same as mass of both A and B are same.
So we can conclude that Box A has 2x the mass of Box B so Box A has more inertia as compared to Box B.
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