In the following question, a sentence is given with

Solution

We are in need of a noun at (A) and a verb at (D). So, 'industry' can be moved to (A) and 'transformed' to (D) to make the respective clauses meaningful. We need a verb in the continuous form at (B), as necessitated by the use of 'has been'. The only one available is 'producing', which can fit here. Then 'processes' can be pushed to (E), completing the phrase 'chemical processes'. The correct sentence is 'For years the petroleum industry has been producing biofuels, using food crops such as sugar cane, corn and soybeans, which are transformed by fermentation or other chemical processes into ethanol or biodiesel'. C is the right answer.