Can a passenger car without intention to overtake, in any case, drive at 100 km/h on a conventional road?

A)Yes, when there is more than one lane in either direction.
B)Yes, when there is fixed separation between the two directions and the maximum limit of 100 km/h is signposted.Correct
C)No.
The general maximum speed for driving on conventional roads is 90 km/h.
That said, on conventional roads with physical separation between the two directions of traffic, the road authority may set a maximum limit of 100 km/h.