The product AB of two matrices A and B is possible if:

1. A and B have the same number of rows.

2. The number of columns of A is equal to the number of rows of B.

3. The number of rows of A is equal to the number of columns of B.

4. A and B have the same number of columns.

For matrix multiplication A × B to be defined, the inner dimensions must match.

If matrix A has the order m × n.And matrix B has the order p × q.The product AB is only possible if n = p.

The number of columns of A is equal to the number of rows of B.

Hence, option 2 is the correct option.