问题
Out of the crowded bus _____, who was wearing a pair of dark glasses. [ ]
A: stepped a tall man in his thirties
B: a tall man in his thirties stepped
C: did a tall man step in his thirties
D: did a tall man in his thirties step
B: a tall man in his thirties stepped
C: did a tall man step in his thirties
D: did a tall man in his thirties step
正确答案是：
