To signal that you are going to perform a manoeuvre, you must keep the light signals on until...
A)other road users have seen the signal.
B)the moment the manoeuvre begins.
C)the manoeuvre is completed.Correct
Manoeuvres must be indicated with sufficient advance notice, using the vehicle's light signals, which must remain on for the entire duration of the manoeuvre, and failing that, with the arm (to be valid they must be performed correctly and be visible). In case of contradiction, the signal made with the arm takes precedence.