The purpose of the fluid catalytic cracking unit (FCCU) in an oil refinery is to:
a. Receive the "reduced crude" and recover more gas oils by further distilling under high temperature and low pressure
b. Remove hydrogen sulphide and nitrogen from the naphtha
c. Cause the heavy hydrocarbons to be transformed into lighter hydrocarbons
d. Remove the propane, butane and light ends from the crude oil
e. Remove the sulphur and nitrogen from the diesel fuel
Answer: C