Mr.smith ()eraly in the morning when he lived in the countryside
选A
used to do sth是过去常常做某事的意思,在这里符合题意,语法正确.
选项C,习惯于早起在语义逻辑上没有问题,但是语法错误,be used to 后面的动词应该用ing形式,所以如果C改为was used to getting up就对了.