by ayang Mon Apr 16, 2007 1:19 pm
Mww,
The question you cite in the Official Guide is a fantastic example of what parallelism means on the GMAT.
In the question, there are 4 elements that are meant to be parallel as "services":
1. mortgages
2. home improvement loans
3. automobile loans and
4. financial advice
The fifth element, "staying within the metropolitan areas" is clearly NOT parallel to the 4 listed above. Logically, staying within the metropolitan areas is not a service in the same way as mortgages, etc.
As a result, the fifth MUST be treated differently and set off from the prior list. Therefore, you would require a "by" or something similar to indicate that the fifth element was not simply the fifth of a list of logically identical elements.
By the same token, the end of the list of 4 elements must be noted with an "and" before the 4th element.
Therefore, the correct answer is, as noted, answer choice (E).
I hope that this is helpful. - Andrew