If AAA and BBB are n×nn \times nn×n matrices and AB=0AB = 0AB=0, which of the following is necessarily true?
A=0A=0A=0 or B=0B=0B=0
det(A)=0\det(A)=0det(A)=0 or det(B)=0\det(B)=0det(B)=0
BA=0BA=0BA=0
AAA and BBB are singular