Which of the Following Statements Concerning the Use of Hydrocarbons

Which of the following statements concerning the use of hydrocarbons as fuels is not correct?

A) The alkane n-octane has an octane number of 100 which indicates its high performance in automobile engines.
B) Catalytic cracking converts straight-chain hydrocarbons that are poor fuels into branched-chain compounds.
C) When poor fuels are used in an engine,combustion can occur before the spark plug fires which results in knocking.
D) The quality of a fuel is indicated by its octane number,and a higher octane number typically results in less engine knocking.
E) none of the above