I had been to a shopping mall this morning, and went through the usual security procedures. One of the security guards did the so-called body check, that is, gently touching you to check if you have something suspicious in your pockets or clothing. (He does this for all the visitors.) He then visually indicated that I could enter the mall, and said, "Thank you, sir".
I smiled and nodded politely without thinking much of it, but I wonder now, what could have been an appropriate verbal response?
The responses given here (Possible responses to "thank you") seem inappropriate in this situation. You can't respond to a body check with "You're welcome", "My pleasure", "Anytime", or "No problem" (or can you?).