Help me with these two difficult sentences

[duc]

Hello everybody,
Please look at the following exercise.Choose the best answers:
1.Many old people don't like change. They are very set in their...
A.life B.habits C.routines D.ways
THe answer to this question is ''D'' but I don't understand why ''B'' or ''C'' is not possible.
2.The government are doing a .......of people's changing habits.
A.plan B.project Cresearch D.survey
THe answer is D but why can't I choose the others?
Please help me with the two sentences above.Thanks in advance!!!!!!!!
_________________
Don't see your shade think you are great

[Mister Micawber]

.
1-- The idiom is set in one's ways.

2-- Only survey fits the grammar of the sentence:

do a survey of
make a plan of
do a project on
do research on
.
_________________
Canadian-American native speaker
who teaches English for a living at Mister Micawber's
ESL cafe: Interview with Mister Micawber