komal wrote:One idea for Social Security reform was to disallow payments for those with a certain level of income; although the idea was rejected, citizens can choose to refuse social security payments for private sources of income, whether derived by pension funds or personal savings, if they want.

(A) for private sources of income, whether derived by pension funds or personal savings
(B) in favor of private sources of income, whether derived from pension funds or personal savings
(C) for private sources of income, whether derived from pension funds or personal savings
(D) and use private sources of income, derived either by pension funds or personal savings
(E) rather than private sources of income, whether derived from pension funds or personal savings

OA C

ididoms all the way

derived from is correct idiom so eliminate A and D
choose x for y is correct one so eliminate C nd E
choose x in favor of y is unidiomatic and wordier way of saying....not accepted

only left is C

OP please mention the source.
IMHO, Source of the problem: Kaplan GMAT Advanced 2009-10 edition.

One idea for Social Security reform was to disallow payments for those with a certain level of income; although the idea was rejected, citizens can choose to refuse social security payments for private sources of income, whether derived by pension funds or personal savings, if they want.

(A) for private sources of income, whether derived by pension funds or personal savings - Right idiom is "derived from"
(B) in favor of private sources of income, whether derived from pension funds or personal savings - Correct idiom would be - refuse one for another, not refuse one in favor of another
(C) for private sources of income, whether derived from pension funds or personal savings
(D) and use private sources of income, derived either by pension funds or personal savings - the easiest error to spot is "derived by" - ELIMINATE
(E) rather than private sources of income, whether derived from pension funds or personal savings - correct idiom would be - refuse one for another, not refuse one rather than another.

i choose C

Knowing that "social security payments" and "private sources of income" are alternatives would definitely help, because "for" can either refer to the citizens (the entity) for whom the payment is intended OR for another source of income.

Since the word "citizens" is clearly mentioned, this Q only tests one of the rarely used idioms "refuse one for another"

hope it helps

komal wrote:
One idea for Social Security reform was to disallow payments for those with a certain level of income; although the idea was rejected, citizens can choose to refuse social security payments for private sources of income, whether derived by pension funds or personal savings, if they want.

(A) for private sources of income, whether derived by pension funds or personal savings - incorrect idiom derived by.ELIMINATE
(B) in favor of private sources of income, whether derived from pension funds or personal savings - incorrect idiom.choose to .. for ...ELIMINATE
(C) for private sources of income, whether derived from pension funds or personal savings - both correct idioms. CORRECT
(D) and use private sources of income, derived either by pension funds or personal savings - incorrect idiom.choose to .. for ...ELIMINATE
(E) rather than private sources of income, whether derived from pension funds or personal savings - incorrect idiom.choose to .. for ...ELIMINATE

OA C

komal wrote:One idea for Social Security reform was to disallow payments for those with a certain level of income; although the idea was rejected, citizens can choose to refuse social security payments for private sources of income, whether derived by pension funds or personal savings, if they want.

(A) for private sources of income, whether derived by pension funds or personal savings
(B) in favor of private sources of income, whether derived from pension funds or personal savings
(C) for private sources of income, whether derived from pension funds or personal savings
(D) and use private sources of income, derived either by pension funds or personal savings
(E) rather than private sources of income, whether derived from pension funds or personal savings

OA C

Even if you don't know the correct usage of Derived from, you can still eliminate A and D.

A - Whether X or Y, X - Derived by, Y - personal ( should be by personal, to maintain ||ism) - ELIMINATED
D - Should be EITHER BY X or BY Y ( to maintain ||ism) - ELIMINATED

IMO : C, 90secs