In efficient driving, it is advised to drive ...

In efficient driving, it is advised to drive ...
A)In high gears and at high revs.
B)In low gears and at high revs.
C)In high gears and at low revs.Correct
Proper gear management is one of the key aspects of efficient driving.
By driving in high gears at low engine revs, fuel consumption is lower.
We should use the highest gear possible (4th or 5th) even in the city, and keep the engine running at low revs.
With low gears, the engine runs at higher revs and will consume more fuel.