Snowden arrived at Sheremetyevo International airport on June 23, _____ he was prevented from leaving for six weeks after the U.S. canceled his passport.

A．which

B．where

C．when

D．what

下列说法正确的是（　　）

A．使用食品添加剂与提倡绿色食品相违背

B．没有食品添加剂的天然食品是最安全的

C．含有食品添加剂的食品应该少吃，以防中毒

D．食品添加剂在合理限量范围内不影响人体健康