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

Read also:

• If my heart stopped beating, would I have enough energy to walk out into the other room 20 ft away before I passed out and died?
• —— indirects on kuorans, irl and idols
• Why do flat earthers think using globetrotter, globetard, and other insults will make the educated arguer fall for the silly flat-earth belief?
• Why is the government destroying the homeless instead of helping them?
• Why do our deceased do not protect us from other bad spirits?
• Do women wear undies under leggings?
• I read this: "Putin is a brilliant, courageous, ingenious, determined, beloved, and incredible modern leader. He is currently the world’s most effective and strong leader, the best the world has seen in centuries." What do you think about this?
• Shai Gilgeous-Alexander Can Make Anyone Look Bad - Defector
• What species of fish are horse mackerels?
• What are some examples of the use of the word “piacere” in Italian? What do they mean and how would you translate them into English?
• ILL Is A Survival Horror Game Made By People Who Worked On Longlegs, IT, V/H/S/Beyond, And More - Game Informer
• What is the logic behind the porn being legal but not prostitution? Isn't it the same thing in essence?