Answer:
B. gerund
Step-by-step explanation:
The infinitive is the "base verb", e.g.: to talk (or just "talk", for the bare infinitive).
The gerund is the, well, form ending in -ing when used as a noun, e.g.: talking as in "Talking to people is usually a pleasant experience for me."
The participle is used to modify something, and ends in -ing (present participle) or -ed (past participle, but some are irregular and don't conform to this!), e.g. talking, as in "That's a great talking point!"
A noun is a noun, it signifies... a thing?