Though widely used for decades to fuel home heating systems

[BTGmoderatorDC]

Though widely used for decades to fuel home heating systems, utility boilers, and industrial furnaces, natural gas has still accounted for far less of the energy consumed in the United States than has oil.

(A) natural gas has still accounted for far less of the energy consumed in the United States than has oil
(B) natural gas has still accounted for far less of the energy consumed in the United States as oil
(C) natural gas still has accounted for far less of the energy consumed in the United States as oil has
(D) still far less of the energy consumed in the United States has been accounted for by natural gas as by oil
(E) still far less of the energy consumed in the United States has been accounted for by natural gas than has oil

[deloitte247]

Option A: Wrong
This is a case of repetition in the underlined sentence to make case for a response which does not offer any describable meaning to the sentence formation in the context it has been used.

Option B: Wrong
Here, the tail end of the argument seeks to conclusively change the meaning of the statement with the contextual usage of ''as'' which could be same as ''replace'' ''in place of'' in The sentence formation.

Option C: Wrong
Here, the placement of the verb ''has'' which is modal auxiliary is a bit misplaced because it doesn't allow the expression to flow more and better . Archaic, obsolete and out-of-date.

Option D: Wrong
The use of ''by'' doesn't seeks to differentiate in measures what ''Natural gas has over oil''. It assumed the same dimension with the use of ''by'' which is a carriage word here.

Option E: Right
Here, the use of ''than'' shows the writer wishes to differentiate in not equal measures the extent of effects one has over the other. It is the most correct of the options.