How is the action of replying to a thanks called?

Question

Imagine the following conversation

Alice: "Here is the document you asked for."

Bob: "Oh, thanks so much."

Alice: "Don't mention it."

So the second person was thanking the first. Afterwards, Alice had a choice of expressions, as illustrated in that question. But is there a name for it? Could one fill the following

After being thanked by Bob, Alice ______________ .

Answer 1

Several answers to the question you linked in your question refer to “acknowledging [receipt of]” the “thank you”:

Alice acknowledged Bob’s show of appreciation with a smile.

(from MacMillan Dictionary, definition 2)