The sign means...
A)mandatory road for buses.
B)bus stop.
C)lane reserved for buses.Correct
The sign in the question indicates a lane reserved for buses that may only be used by collective transport vehicles. When the sign displays the word Taxi, it also authorises taxis to use the lane.
In some cases, when the lane is delimited by a broken line, it may be used by other vehicles, but only to carry out a manoeuvre other than stopping, parking, overtaking or changing direction, and always giving priority to vehicles that are permitted to travel in that lane.
This sign must not be confused with the bus stop sign.