To meet a government requirement, a bottler must test 5 percent of its spring water and 10 percent of its sparkling water for purity. If a customer ordered 120 cases of spring water and 80 cases of sparkling water, what percent of all the cases must the bottler test before he can send it out

A．6.5%

B．7.0%

C．7.5%

D．8.0%

E．(E) 8.5%