She is interested in the ... of old buildings

1,she is interested in the... of old buildings
a, preservation b,preservative c,preserve d,preserved
2, this exercise... carefully
a,must done b,must be done c,must do d,must be do
3, she stayed at home ... It rained so heavily
a,because b,however c,though d,and
4, Bi is... boy in the class
a,taller b,the tallest c,tall d,tallest
giup minh voi​