Field audits are the most comprehensive type of IRS examination, and these audits are conducted by highly trained IRS employees, typically with many years of experience. Which of the following will provide the insight and information most likely to help you when preparing to represent a client in a field audit interview?

Audit Techniques Guides (ATGs).

Circular 230.

The Examining Process section of the Internal Revenue Manual (Part 4).

IRS private letter rulings