Concept:The phrase "bringing up old memories" uses a common phrasal verb that means to recall or introduce past experiences.Explanation:The correct phrasal verb is "bring up", which means to raise a subject or cause something to be remembered. It is natural to say "bringing up old memories" when someone mentions events from the past. Option C, "up", completes the idiom correctly. The other options do not form a standard expression with "memories". Therefore, "bringing up old memories" is the correct idiomatic choice.Answer:C. up