肉毒菌的感染途径是

A．污染伤口

B．食用污染食物

C．节肢动物叮咬

D．接触肉毒患者的用品

E．吸入污染的空气

It is obvious to the students _____ they should get well prepared for their future. [ ]

A. as

B. which

C. whether

D. that