Amit-

Great question!

The concept here, as you mentioned, has to do with countable versus uncountable modifiers. If I am modifying (i.e. describing-modifiers simply describe!) a noun that is countable (i.e. I am able to numerically calculate how MANY there are of that noun), then I must use a certain set of modifiers to describe those nouns.

For example:

MANY neutrons
AS MANY neutrons AS protons
FEW neutrons
FEWER neutrons THAN electrons
NUMBER of neutrons

Since I can count the number of neutrons (or hats, or dollars, or basketballs), the above set of modifiers are the ones I must use.

On the other hand, sometimes I must modify (describe) nouns that are uncountable. The big-time ones that the GMAT loves to test are 'water' and 'money.' And although I can count GALLONS of water or DOLLARS, I cannot count 'water' or 'money.' So we must modify these uncountable nouns by using:

MUCH water
AS MUCH water AS alcohol
LITTLE water
LESS water THAN alcohol
AMOUNT of water

And this makes a lot of sense if you take it out of context! I would never say "I have as many money as Bill Gates." That is grammatically incorrect. Instead, I would say "I have as MUCH money as Bill Gates," and although I would be lying, I would be grammatically correct.

So, if you've determined that your noun is uncountable, I must choose from the above list of uncountable modifiers to describe it.

In the GMAT example you gave, water is uncountable and services are countable. (This distinction is not trivial! 'Services' is plural and since I am counting more than one service to make it plural, it is implied that this is a countable noun. 'Water' is your textbook example of an uncountable noun). Thus, I can start eliminating answers based on the countable and uncountable modifiers used in each:

A) The constructions tells me that the modifier 'little' applies to both water and services. I cannot use 'little' to modify services.
B) Same problem as A.
C) No modifier issue-this is the correct use of modifiers.
D) Same problem as A and B.
E) No modifier issue - this is the correct use of modifiers.

So that leaves us with B and E. But the verb in C (exists) is in the singular form, whereas the subject (few services and little water) is plural (remember, the word AND guarantees a plural subject! Every time!). Thus, I can eliminate C based on a Subject-Verb disagreement (the verb is singular while the subject is plural), and I am left with E.

Note that E is LEAST concise of these answers, and that it does not sound ideal by any means. I love this problem for that reason. It is very typical of the GMAT to give you answers that may sound wordy and clunky at first glance, but these answers are grammatically correct. This reinforces the idea that on Sentence Correction, you should work by confidently eliminating wrong answers rather than going straight for the right answer.

I hope that helps!

-Dan Lerman
Manhattan Prep