When turning, you should signal early.
Whenever you intend to turn or change lanes, start to signal well in advance and keep signaling until you've completed the maneuver. Then turn off your signal if it hasn't already turned off by itself.
B You should use your turn signals to mark your vehicle when it is off on the side of the road.
C You do not need to use your turn signals when changing lanes in traffic on a four-lane highway.