Which fossil fuel once contributed a great deal to electricity generation in the 1970's (United States) but is only ~1% derived now?

A) peat

B) lignite coal

C) petroleum and its derived-fuels

D) oil sands

E) oil shale

C) petroleum and its derived-fuels

Explanation:

In 1970's, majority of power production was carried out using petroleum and its fuels derived from it. As, the decade proceeded, oil crisis stroke the World. Due tom which, oil prices were gone up significantly which was then replaced by the other fuels coal and natural gas etc. later on.