A crest (cambio de rasante) is:

A)A section of road where there is a change of direction.
B)A section of road where the full width of the carriageway cannot be seen.
C)A place where two sections of road with different gradients meet.Correct
A crest is a place where two sections of road with different gradients meet. When, due to its configuration, we cannot see vehicles travelling in either direction, it is called a crest with reduced visibility. On these road sections we are required to reduce speed, and it is prohibited to encroach on the left-hand side of the carriageway, change the direction of travel, turn left, stop or park.