Choice "B" is correct. Position papers are endorsed and strongly recommended but are not considered mandatory guidance of the International Professional Practices Framework (IPPF). The IPPF is composed of mandatory and endorsed/strongly recommended authoritative guidance as follows:Mandatory

• Definition of internal auditing

• Code of Ethics

• International Standards for the Professional Practice of Internal Auditing

Endorsed and strongly recommended

• Position papers

• Practice Advisories

• Practice Guides

Choice "a" is incorrect. The definition of internal auditing is considered mandatory authoritative guidance of the International Professional Practices Framework (IPPF).
Choice "c" is incorrect. The Code of Ethics is considered mandatory authoritative guidance of the International Professional Practices Framework (IPPF).
Choice "d" is incorrect. The International Standards for the Professional Practice of Internal Auditing are considered mandatory authoritative guidance of the International Professional Practices Framework (IPPF).