What code do I use on schedule C for an independent contractor mystery shopper

I did a small amount of work in 2021 as a mystery shopper but cannot find the right code. I entered a code I thought would fit from the list and on schedule C it gets rejected and TT keeps asking to fill in the code. I cannot figure out how to fill out this form without being guided. I don't understand why I am let on my own with this form that is attached to the 1099 NEC.  Everything I try gets rejected. I realize that most of the info is my own, my address, my name. It asks for TAX ID number. I tried my own, I tried the company who paid me, nothing works. 

Frustrated. I just want to get this last info in to file my tax! Can anyone help?