My take is C:
A. new police patrolling program is effective in controlling burglaries
Not sure whether the alarms were effective as well, but people had the alarms installed. Even if the program is not effective, people know that paroling progarm is an alternate to the alarms.
B. most people supported the new police patrolling program
Doesn't matter whether people supported the program. It is in place. Therefore, OOS.
C. people's perception of the threat of burglaries decreased because of the new police patrolling program
This option seems correct. Yes, people have started believing that patrolling program is in fact reducing burglaries, hence they have stopped buying the alarm. Negate it .. people believe that patrolling hasn't decreased the burglaries, they wont stop buying the alarms.
D. people thrust the police patrolling vehicles more than they trust burglar alarms.
People may trust patrolling vehicles more, but is it to the extent that they stop buying alarms. Do they believe, they need both alarms and patrolling vehicle or just patrolling vehicle ( so that they stop buying the alarms) - not clear. Hence, not a good answer choice.
E. people have formed an opinion that even the most advanced burglar alarms cannot help prevent robberies because the burglars have become more technologically advanced.
If people have formed an opinion that alarms don't work, then, even if the patrolling happens or not, they wont buy the alarms. In this case, patrolling is not a reason that they stopped buying alarms. This seems to be a kind of weakener.