For Calculating Decimal Output of  125 * A - 100 * (A Mod 4) + 2 with having A ( a one BCD digit) Which of the following is True?

1) we need at least two decimal adder.

2) we need at least two 4-bit binary adder.

3) we need at least one decimal multiplier and one decimal adder.

4) Non of the above.

Why our instructor select (4) as a solution and not selected (3)? any idea or hint?

thanks to all.