The most appropriate response explaining why \( \frac{ad + bc}{bd} \) is a rational number is:
By the Closure Property, \( ad + bc \) and \( bd \) are both integers, and so the fraction with numerator \( ad + bc \) and denominator \( bd \) is a quotient of two integers.
This response correctly identifies that both the numerator and the denominator are integers, which means the entire expression \( \frac{ad + bc}{bd} \) is a rational number, as rational numbers are defined as the quotient of two integers (where the denominator is not zero).