Answer: choice A
Step-by-step explanation:
You have to multiply each row by its corresponding column.
For example you multiply 1*5 and put it in the first row and first column(a1b1). you multiply 5*5 and put it in the second row and first column(a2b1) and so on.
when multiplying a 3*1 matrix by a 1*3 matrix you’ll get a 3*3 matrix.
