The volume of water that goes into the hose is the same as the volume of water that comes out the nozzle. This means the velocity is inversely proportional to the area. The area is proportional to the square of the diameter.
Taken together, these facts mean that if the diameter is divided by a factor of 3, the velocity is multiplied by a factor of 3^2 = 9.
Nozzle velocity = 3^2 * entering velocity
.. = 9 * (4 m/s)
Nozzle velocity = 36 m/s . . . . . . . . . corresponding to selection A