Let a/b and c/d represent two rational numbers. this means a, b, c, and d are (integers or irrational numbers), and b and d are not 0. this product of the numbers is ac/bd, where bd in not 0. both ac and bd are (integers or irrational numbers), and bd is not 0. because ac/bd is the ratio of two (integers or irrational numbers), the product is a rational number. choose from one of the two options from the ()

All of the answer choices are "integers"

a,b,c,d are integers, which is basically the set of positive or negative whole numbers. Though they make the restriction that b and d are not zero

a*c is an integer, so is b*d. This is due to the closure property of multiplication of integers (multiply any two integers you want and it leads to another integer)

ac/bd is the ratio of two integers (ac and bd) where bd is nonzero