For complex numbers Z1, Z2 which one of the following is true ____?

arg (Z1 Z2) = arg Z1 + arg Z2

arg (Z1 Z2) = arg Z1 - arg Z2

arg (Z1 Z2) = arg Z1 . arg Z2

None of these

The argument of the product of two complex numbers is the sum of their arguments.

This property comes from the multiplication of complex numbers in polar form.