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

Read also:

• How do I identify fake friends in life?
• Have you ever lied to your family? What were the circumstances?
• Everyone says the pet population is out of control. Everyone says you MUST spay or neuter your pets. No one wants to talk about how its almost $1,000 to spay or neuter a pet. Why is it so expensive if its so necessary? Animal shelters do it for free.
• What is the most heartbreaking or sad love story that you ever had (experienced)?
• Famous 'ice-age puppies' are not actually dogs, according to new study - Earth.com
• Have you ever had sex with sisters?
• What sets porcini mushrooms apart from other types of mushrooms, such as button mushrooms?
• How did you react when your doctor ordered a colonoscopy?
• What is something brutally honest that needs to be said?
• California schools are very liberal. Do you think California schools are teaching students to hate Republican views (views on: God, guns, prayer, secure borders, etc.)?
• There is any scientific evidence that we live in a sphere. Why do others say that we lives in a flat Earth but there is no evidence that they have proven the existence of a flat earth?
• I told my 13-year-old daughter that she should never start a fight, but has my permission to end it. She got suspended for ending a fight that some other girl picked with her by hitting her then retreating. How do I handle the school’s response?
• What are some of the differences between the Democratic and Republican parties? What policies does each party advocate for? What groups do these parties usually represent?
• I'm looking for an answer from people who consider themselves "Gender Critical", or transphobic, or TERFs, and my question is this - Why would you refuse to use the pronouns someone wants? What does it cost you? Where's the harm?