Lemme take a shot before you get the 'official' answer from Mike himself
Sorry mate, but ur understanding is severely flawed. I wud say, the wrong understanding was in turn wronged again in Point#2 above. I will try to explain how-
As you correctly identified the split is at two points- Comparison and Few vs Less.
1)
Comparison: The comparison is between the workforce of 2008 and the workforce of 2009. And not between the
values of the workforces. There is no indication in the underlined portion that tells us that this portion modifies the number 2500 (it just happens to be the last thing before comma).
2)
Less vs Few: Please understand that
Workforce is different from Workers. In fact, Workforce is the
number of workers. And we would treat Workforce as uncountable and Workers as countable. You dont say 1 workforce or 2 workforces. But you say 1 worker, 2 workers etc. Please consider the below eg.
The number of workers was 10 less than the number of workers last year -Comparing numbers (eg. 20 is
less than 30 and not fewer)
There were 10 fewer workers than there were last year. - Comparing workers
Therefore, a Workforce is less than and Workers are fewer than.
Now, wen is say that '
wrong understanding was, in turn, wronged again in Point#2', i meant that even if you got the comparison wrong and compared
Values, you will have to use Less and not Few. Because
a value is always Less than another one and not Fewer than. In fact, its not about the number attached but the entity that is being compared that will decide whether its countable or uncountable.
From your eg above-
5 miles is countable but Distance is uncountable (therefore Less than). And therefore, The
distance is 5 miles
less.
10 pounds is countable but Money is uncountable (therefore Less than). And therefore, The
money is 10 pounds
less.
Similarly,
5 Workers is countable (therefore Fewer) but Workforce is uncountable (therefore Less than)
Coming to the question, since its Workforce that is being compared and Less than that should be used. IMO, the correct answer should be C.
Hope this helps.