The sign indicates that...
A)you cannot move laterally either to the right or to the left.
B)you must travel in the direction indicated by the arrow, since it is a one-way carriageway.Correct
C)changing direction is prohibited.
The sign in the question indicates that, on the carriageway that extends in the direction of the arrow, vehicles must travel in the direction indicated by it, with travel in the opposite direction being prohibited. We could change direction but not the sense of travel.
If the sign is circular, then we must mandatorily follow the direction and sense indicated by the arrow.