When is a vehicle travelling at an abnormally reduced speed?

A)When travelling at a speed lower than the maximum permitted speed.
B)When travelling at a speed higher than the minimum permitted speed.
C)When travelling at a speed lower than the minimum permitted speed.Correct
Travelling at an abnormally reduced speed is considered to occur when driving below the minimum speed without a justified reason.
The minimum speed on motorways and dual carriageways is any speed below 60 km/h. On all other roads, it is any speed below half the generic maximum assigned to each vehicle category.
There are sections where the minimum speed that must be observed will be specified.
The sign in the photo, minimum speed, requires vehicle drivers to travel at least at the speed indicated by the figure in km/h, from the point where it is placed until another minimum speed sign of a different value, or an end of minimum speed sign, or a maximum speed sign of equal or higher value.