Which of the following is NOT listed as a light oil

A．Crude oil is found below land and water.
B．Crude oil is always found a few hundred feet below the surface.
C．Pumping and pressure force crude oil to the surface.
D．A variety of petroleum products is obtained from crude oil.

A．By expansion of the hydrocarbons.
B．By pressure and pumping.
C．By vacuum created in the drilling pipe.
D．By expansion and contraction of the earth's surface.