Which of the following is a rational number? \( \sqrt{60} \sqrt{70} \sqrt{4} \sqrt{8} \)

To determine if \( \sqrt{60} \sqrt{70} \sqrt{4} \sqrt{8} \) is a rational number, we can simplify the expression first. We know that \( \sqrt{4} = 2 \). Therefore, the expression becomes \( \sqrt{60} \sqrt{70} \cdot 2 \sqrt{8} \). Since \( \sqrt{8} = 2\sqrt{2} \), we can replace \( \sqrt{8} \) to get \( \sqrt{60} \sqrt{70} \cdot 2 \cdot 2\sqrt{2} = 4 \sqrt{60} \sqrt{70} \sqrt{2} \). The square root of a product of non-perfect squares, such as \( 60 \times 70 \times 2 \), will not resolve to a rational number since it retains an irrational component, hence it cannot be simplified further into a rational number. Thus, the answer is that \( \sqrt{60} \sqrt{70} \sqrt{4} \sqrt{8} \) is not a rational number, as it ultimately includes an irrational element in its simplification.