In a serpentine exercise, which of the following actions is not penalized?

In a serpentine exercise, activating the wrong turn signal is not considered a penalized action. The purpose of this driving exercise is primarily to assess a driver's ability to control the vehicle through a series of cones or markers in a winding path. While signaling is important for safe driving, the specific requirement during the serpentine exercise focuses more on the overall maneuverability and control of the vehicle rather than the accuracy of the signals used.

The other actions mentioned, such as failing to signal, driving outside the marked lanes, and improper use of mirrors, directly impact safety and control during the exercise and therefore are penalized. Failing to signal creates confusion for other drivers, while driving outside the marked lanes indicates a loss of control. Improper use of mirrors, which may lead to inadequate awareness of surrounding vehicles or obstacles, also results in a penalty since situational awareness is crucial for safe driving.