If AAA and BBB are n×nn \times nn×n matrices and AB=IAB = IAB=I, which of the following must be true?
det(A)=det(B)\det(A) = \det(B)det(A)=det(B)
det(A)det(B)=1\det(A) \det(B) = 1det(A)det(B)=1
det(A)=0\det(A) = 0det(A)=0
det(A)+det(B)=0\det(A) + \det(B) = 0det(A)+det(B)=0