Answer:
The correct answer is B: use irony to change the audience's mind about a misconception.
Step-by-step explanation:
The heading "A Fed Bear is a Dead Bear" contains irony and its purpose is to explain to the audience that they should not leave food unattended, because of the bears. If bears obtain human food, they probably will be destroyed (killed) or removed from the park.
The author of the heading uses irony to explain to the readers how serious their actions might be for the bear's life, so they could pay attention to their food and preserve their safety and bear's life.