What is the maximum speed at which one may drive on a dual carriageway within a built-up area?

What is the maximum speed at which one may drive on a dual carriageway within a built-up area?
A)120 km/h.
B)80 km/h.Correct
C)100 km/h.
On a motorway or dual carriageway the maximum speed is 120 km/h, but if it is within a built-up area, this speed is reduced to a maximum of 80 km/h.