Which pair of complex factors results in a real number product? 15 (-15i) 3i (1 - 3i) (8 + 20i) (-8 - 20i) (4 + 7i) (4 - 7i)

D. (4+7i) (4-7i)

(4 + 7i) (4 - 7i)

Step-by-step explanation:

This pair will produce a real answer because they are complex conjugates.

Complex conjugates (a+bi) (a-bi) when multiplied together form a real number (a^2 + b^2)