pyq/2013/csat/32

Read the following passage and answer the two items that follow:

Crude mineral oil comes out of the earth as a thick brown or black liquid with a strong smell. It is a complex mixture of many different substances, each with its own individual qualities. Most of them are combinations of hydrogen and carbon in varying proportions. Such hydrocarbons are also found in other forms such as bitumen, asphalt, and natural gas.

Mineral oil originates from the carcasses of tiny animals and plants that lived in the sea. Over millions of years, these dead creatures formed large deposits under the sea-bed; and ocean currents covered them with a blanket of sand and silt. As this material hardened, it became sedimentary rock and effectively shut out the oxygen, preventing the complete decomposition of the marine deposits underneath. The layers of sedimentary rock became thicker and heavier. Their pressure produced heat, which transformed the tiny carcasses into crude oil in a process that is still going on today.

Questions:

Mineral oil deposits under the sea do not get completely decomposed because they:

(A) are constantly washed by the ocean currents.

(B) become rock and prevent oxygen from entering them.

(C) contain a mixture of hydrogen and carbon.

(D) are carcasses of organisms lying in saline conditions.