What document describes the important requirements of the AWS Certified welding inspector program?
a) AWS D1.1/D1.1M: Structural Welding Code – Steel
b) AWS A2.4: Standard Symbols for Welding, Brazing, and Nondestructive Examination
c) AWS B2.1: Specification for Welding Procedure and Performance Qualification
d) AWS QC1: Standard for AWS Certification of Welding Inspectors