Each number in the list below can be paired with a different number in the same list to make an integer product except for one number. What is the letter corresponding to the one exception? A. $\sqrt{40}$ B. $\sqrt{54}$ C. $\sqrt{60}$ D. $\sqrt{90}$ E. $\sqrt{96}$ F. $\sqrt{120}$ G. $\sqrt{135}$
