Let \(A\) and \(B\) be two square matrices of order 3 and \(A B=O_{3}\), where \(O_{3}\) denotes the null matrix of order 3 . Then,
(A) must be \(\mathrm{A}=\mathrm{O}_{3}, \mathrm{~B}=\mathrm{O}_{3}\)
(B) if \(\mathrm{A} \neq \mathrm{O}_{3}\), must be \(\mathrm{B} \neq \mathrm{O}_{3}\)
(C) if \(\mathrm{A}=\mathrm{O}_{3}\), must be \(\mathrm{B} \neq \mathrm{O}_{3}\)
(D) may be \(\mathrm{A} \neq \mathrm{O}_{3}, \mathrm{~B} \neq \mathrm{O}_{3}\)
