Final answer:
A sign of increasing skill as a driver is making correct decisions before being instructed by a supervisor, which shows improved anticipation and situational awareness, ultimately leading to responses that become automatic over time.
Step-by-step explanation:
One way of telling that you are becoming more skilled as a driver is A. You make correct decisions before your supervising driver tells you what to do. This indicates you are developing situational awareness and the ability to anticipate and address driving scenarios proactively, which is a key sign of increased skill and experience. Over time, driving responses become more automatic, allowing you to encode additional information about this skill with less conscious effort, as mentioned in the provided passage. This is similar to performing other routine activities on 'autopilot,' where complex tasks are accomplished with minimal concentration.