nice one!! please refer to the danaz's post below..

IMO A

I think it's A here, even though E might be a close second. We are told in the last sentence that the only factor associated with a crime-rate drop is a decrease in the number of people in the community aged fourteen to thirty. If that's the case, then seeing effects in a short period of time will be unlikely. Maybe in some years, the population is much older and therefore less inclined to commit crimes.

B doesn't work because increasing the penalty would actually be a good thing, which would discourage crime.

C is out as well because taking that sort of measure means reducing the number of young people in town, which will lead to fewer crimes.

D is somewhat similar to C, but in a much more tangential way. If you increase the age at which students are permitted to leave school, you are basically forcing them to stay in the community for longer, which will of course translate into crimes.

E again, gives the youth reason to stay in the community and would therefore be ineffective against crime.

IMO A

IMO A

Should be 'A'.

That's the only option for which you can say that the steps taken will not help in achieving the desired result.

I think A is the best in this case.