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.

If the orders of matrices A and B are m × n and p × q respectively, then which of the following is true for the product BA?

1. m = p

2. m = q

3. n = p

4. n = q