Xiaobaitu: I need your Help with 485 RFE

The RFE question is "you indicated that you were not inspected upon entering the United States, please explain"

The INS sent me a copy of the original I-485, and I found I did make a mistake when I was filing out the original I-485 form, i.e., to the question in I-485 (part 3) "were you inspected by a US immigration officer?", I answered no.

What's your advice to respond to this RFE? what documents should I provide to convince the officer that I was inspected and that was only a mistake?

Thanks a lot!