The auto ignition in a spark ignition engine means

automatic ignition of the charge at the end of compression

ignition induced by the passage of a spark

ignition of the charge before the passage of flame front

ignition induced to supplement the process of normal combustion

reduce the resistance to sliding that occurs between the cam and the tappet.

allow for lengthening of the valve owing to the heat of combustion

increase the speed at which the valves move up and down

make the crankshaft turn smoothly

overheating of the engine

incomplete valve closure

fouling of spark plug by gasoline

none of these

screw pitch gauge

engineering scale

feeler gauge

vernier caliper

four stroke I.C. engines

two stroke I.C. engines

V-6 engines

none of these