What is an appropriate response to someone saying "merci" in French?

Read also:

• What shouldn't you Google?
• New Orleans Saints sign RB Cam Akers to one-year contract - New Orleans Saints
• What is a common thought that keeps people up at night? Why do some people experience this?
• How do the Sola Scrptura folks react to the Dead Sea Scrolls and other more recent discoveries of ancient Biblical texts not among those canonized by Martin Luther?
• In what ways Indian parents are destroying their children's life?
• What are the defining characteristics of woke liberals and conservatives in the United States?
• Why do companies cull employees during financial downturns without saying so?
• If you believe in God, do you think God can save you from cancer?
• A high-resolution spectrometer that fits into smartphones - Phys.org
• Why do we still feel attached or jealous when a covert narcissist moves on, even after realizing their toxicity and the suffering they caused?
• Why would my husband cheat on me with an ugly fat woman?
• Was there any slavery of white people that actually compares to the transatlantic slave trade? I’m not baiting or anything actually genuinely curious and want to know.