Driving on a freeway at 120 km/h in heavy rain is driving at a speed that is...

Correct answer: inappropriate for the conditions.

For a passenger car, 120 km/h is the speed limit on a freeway, so you are not exceeding it. But heavy rain reduces traction and visibility, and at that speed you would not be able to stop in time for an obstacle. That speed is inappropriate for the conditions, and you must slow down until you can stop within the distance you can see.

Real Decreto 1428/2003, de 21 de noviembre, por el que se aprueba el Reglamento General de Circulación · Con lluvia, mantenga el control