Which of the following is a recommended measure for fuel saving?

Which of the following is a recommended measure for fuel saving?
A)Descend slopes with the engine in neutral.
B)Drive with the lowest possible gear.
C)Switch off the engine during prolonged stops.Correct
Switching off the engine during prolonged stops, since it is not running, is a good measure to save fuel.
Descending slopes in neutral is an incorrect measure for fuel saving, because the engine at idle also consumes fuel, while travelling with a gear engaged at more than 20 km/h without accelerating would consume nothing.
Driving with low gears does not save fuel either; on the contrary, it will skyrocket consumption.