Each bank in the town of La Rinconada has only a single set of locking doors at its entrance. In the town of Inverness, on the other hand, the entrances to nearly all banks are equipped with two sets of locking doors, operated by a mechanism that allows only one set of doors to be open at a time. It is clear, then, that banks in Inverness experience more robbery attempts than do those in La Rinconada, and have thus adopted the extra doors as a security measure.

Which of the following, if true, most weakens the argument above?

a) Last year the number of bank robberies in La Rinconada was almost one-half greater than the corresponding figure for the previous year.
b) Inverness is known for its harsh winters, while the climate of La Rinconada is quite temperate year-round.
c) The mechanism of the double doors used by banks in Inverness allows bank security personnel to lock the doors remotely.
d) Bank robbery attempts are typically unsuccessful, and, even when the robbers do manage to escape with stolen money, the sum is usually quite small.
e) Inverness has almost twice as many police officers per capita as does La Rinconada.

Why is A) not a weakener? If the # of bank robberies in La Rin is > that in Inverness, the security is obviously out of question.

OA is B

A.Last year the number of bank robberies in La Rinconada was almost one-half greater than the corresponding figure for the previous year

The comparison is between Number of robberies in La Rinconada for last year and the year before that.
It doesnt talk about the number of robberies in Inverness.
Hence A doesn't weaken. In fact this option doesn't help us at all.

Hope the explanation helps.

Note also that the number of bank robberies isn't useful unless we know the number of banks! Twice as many bank robberies in a city with four times as many banks actually represents a city that is twice as safe.

There are plenty of reasons to rule out A), since it doesn't mention Inverness at all, but the # vs. % error is a classic issue that shows up on the GMAT again and again--keep your eyes out for that pattern!
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Each bank in the town of La Rinconada has only a single set of locking doors at its entrance. In the town of Inverness, on the other hand, the entrances to nearly all banks are equipped with two sets of locking doors, operated by a mechanism that allows only one set of doors to be open at a time. It is clear, then, that banks in Inverness experience more robbery attempts than do those in La Rinconada, and have thus adopted the extra doors as a security measure.

Which of the following, if true, most weakens the argument above?

a) Last year the number of bank robberies in La Rinconada was almost one-half greater than the corresponding figure for the previous year. Incorrect - does not talk anything about the town of Inverness.
b) Inverness is known for its harsh winters, while the climate of La Rinconada is quite temperate year-round. Correct - Inverness banks have two doors to manage the temperature inside the bank and they are not specifically meant to control robbery. It has a direct effect on the conclusion.
c) The mechanism of the double doors used by banks in Inverness allows bank security personnel to lock the doors remotely. Incorrect - looks like the answer but not. Although it looks like an alternative reason, locking remotely or manually does not matter. The point does not weaken the conclusion.
d) Bank robbery attempts are typically unsuccessful, and, even when the robbers do manage to escape with stolen money, the sum is usually quite small. Incorrect - does not weaken. sum of money does not matter.
e) Inverness has almost twice as many police officers per capita as does La Rinconada. Incorrect - number of police officers does not affect the conclusion.

B clearly is the winner.

It provides different cause than that mentioned in the Premise. The author while arriving at a conclusion believe that only 1 cause can lead to the effect. If different cause is having the same intended effect, author's conclusion will gets weakened.
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If the official answer really is B, this is a terrible question. Answer choice C gives a very plausible reason why the bank set up two doors rather than just one. For B, we have to make a huge assumption that the number of door locks is directly related to the quality of weather control inside a bank.

For answer B, climate may explain why a two-door system is desirable, but it does nothing to explain why a double-locking system is desirable. Even if B is true, Inverness banks still have twice as many locks on their doors as do La Rinconada banks. So I'm not sure how B weakens the argument that Inverness banks have greater security concerns than do La Rinconada banks.

After all, the argument isn't saying "Inverness banks have two doors and La Rinconada banks only have one. Therefore Inverness banks have greater security concerns than La Rinconada banks". That would be a ridiculous argument, since it's pretty easy to walk through a door. The argument is based specifically on the fact that Inverness banks have two *locked* doors. The right answer to this question absolutely needs to address that point.

But answer C is the only other remotely plausible candidate, and to even contemplate C, I need to start making a lot of assumptions about bank security protocols. Making certain assumptions, you might be able to claim that C offers an alternative reason (besides additional security) for choosing double-locking doors. Perhaps remote lock operation leads to cost savings, or added convenience for bank personnel, and that's the reason Inverness banks chose them instead of single-locking doors. That seems extremely tenuous to me, though, so I dislike C as an answer here. But I think B is also quite a bad answer to this question if it is indeed the OA, since B only addresses a completely unimportant part of the original argument.
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