Final answer:
You should use your four-way flashers when slowing down unexpectedly and when coming to a complete stop on a roadway or its shoulder.
Step-by-step explanation:
The appropriate time to use your four-way flashers is both A and B.
You should use your four-way flashers when slowing down unexpectedly and when coming to a complete stop on a roadway or its shoulder.
These situations help to alert other drivers of your actions and ensure safety on the road.