All passengers ______ go through safety check before they take a

All passengers ______ go through safety check before they take a plane.
A、can
B、may
C、must
D、ought
【正确答案】：C
【题目解析】：试题分析：can能，能够；may可以，可能；must必须，一定；Ought应该。句意：所有乘客在上飞机之前都要经过安检。故选C。