After Crude Oil Is Pumped Out of the Ground, It

After crude oil is pumped out of the ground, it must be processed in a "cracking tower." The tower separates it into less dense chemicals like butane and gasoline, and more dense chemicals like diesel fuel and tar. Based on this information, crude oil can best be classified as a

A) pure compound.
B) mixture of compounds.
C) mixture of pure elements.
D) solution of plasma and liquid.