Which statement is always true? a) the sum of two irrational numbers is rational. b) the product of a rational and irrational number is rational. c) the sum of two rational numbers is irrational. d) the product of two rational numbers is rational.

The answer is D.

for A, it's possible for two irrational numbers to add to a rational number, but it's not always true.

for B, same situation, it could be, but it's not always true.

for C, adding two rational numbers will never result in an irrational number. so this one is wrong.

D is always true, and by process of elimination, it must be this one.