1. (1) Preignition is caused by improper ignition timing. (2) Detonation occurs when an area of the combustion chamber becomes incandescent and ignites the fuel/air mixture in advance of normal timed ignition. Regarding the above statements, A. only No. 1 is true. B. both No. 1 and No. 2 are true. C. neither No. 1 nor No. 2 is true.