You can either,

Multiply the four choices a,b,c,d out.

or find each of there determinants.

If B is the inverse of A then AB= I

So the answer will be what two matrix multiply together to give the identity matrix.

Finding their determinants you say B is the inverse of A and Det(A) = 2, then Det(A^{-1})=Det(B)=1/2

This means Det(A)Det(B)=1 which means A and B are inverses.

I'd probably multiply them all out its good practice