Final answer:
The appropriate action when a traffic signal changes from green to amber is to stop if it is safe to do so. Speeding up, maintaining speed, or ignoring the signal altogether are not recommended and can lead to traffic violations or accidents. Option c) Stop if you can do so safely is correct.
Step-by-step explanation:
If the signal changes from green to amber as you approach the intersection, the correct action to take is to stop if you can do so safely.
This means that you should begin to slow down and prepare to come to a complete stop before the intersection, as long as stopping can be done in a way that doesn't pose a risk to vehicles behind you (for example, if they have enough distance and time to stop as well).
It is important not to try to speed up to clear the intersection, as this can pose a danger to yourself and others, particularly if the light changes to red before you complete the crossing.
Maintaining your speed or ignoring the signal are also incorrect because they can lead to traffic violations or accidents.
Therefore, Option c) Stop if you can do so safely is correct.