Directions: In the question below, the first and the last (correctly ordered) sentences are numbered 1 and 6, respectively. The rest of the passage is split into four parts and named B, C, D and E. These four parts are not given in the proper order. Choose the correct combination from amongst the given alternatives.

1. Biofuel is any fuel that is derived from biomass — plant material or animal waste. B. Biofuel is perceived by its advocates as a cost-effective and environmentally benign alternative to petroleum and other fossil fuels. C. Primarily because of rising petroleum prices and increased concern over the contributions made by fossil fuels to global warming. D. Since such feedstock material can be replenished readily, biofuel is considered to be a source of renewable energy. E. Many critics express concerns about the scope of the expansion of certain biofuels.
2. Mainly because of the economic and environmental costs associated with the refining process and the removal of vast areas of arable land from food production.