Final answer:
A pulp polyp is a proliferative reaction of the pulp tissue in response to long-standing irritation, often not associated with severe pain and not specifically found in the elderly.
Step-by-step explanation:
A pulp polyp, also known as chronic hyperplastic pulpitis, is B. a proliferative reaction of the pulp. It is typically a response to long-standing irritation, leading to an overgrowth of the pulp tissue that can protrude from the cavity of decayed teeth. Despite the rather dramatic appearance, it is not typically associated with severe pain because it is a chronic lesion with an adequate blood supply; therefore, choice D is incorrect. It is not specifically associated with elderly patients, hence option C is also incorrect, and while it is a pathological change, it is not considered an acute lesion, making option A incorrect as well.