If A is matrix of order m × n and B is a matrix such that AB’ and B’A are both defined, then order of matrix B is
As AB’ is defined. So, B’ must have n rows.
∴ B has n columns.
And, B’A is also defined. As, A’ has order n × m
∴ B’A to exist B must have m rows.
∴ m × n is the order of B.
Option (D) is the correct answer.