Which of the following is least likely to be the start of a social engineering attack?

A$.$ While waiting for coffee near your work, a fellow patron asks you where you work. He tells you he's on his way to interview there. He follows you back to work chatting about the company. He assumes that you will let him in using your access code.

B$.$ You are at a marketing conference and a fellow attendee attending the same seminar asks you which company you work for.

C$.$ You are in the elevator on your way to work and you see a nice$-$looking thumb drive on the floor of the elevator.

D$.$ fellow you aren't familiar with tells you that he's been sent by IT to install updates to your omputer. He lets you know it will take about $20$ minutes and to feel free to take a short break vhile he does it$.$