To achieve efficient driving, you should travel...
A)continuously varying your speed, so that the engine does not become fatigued.
B)using the lowest gears as much as possible.
C)at a uniform speed, avoiding braking and sudden acceleration.Correct
To achieve efficient driving, speed must be kept as uniform as possible, avoiding unnecessary acceleration and braking. It is not a matter of driving faster or slower, but of maintaining a constant average speed for as long as possible.
Proper gear management is another key aspect of efficient driving.
Driving in higher gears at low engine revs results in lower fuel consumption.
You should use the highest gear possible (4th or 5th) even in the city, and keep the engine running at low revs.
With lower gears, the engine runs at higher revs and will consume more fuel.