A primary purpose of a reference standard is:

• A. To provide a guide for adjusting instrument controls to reveal discontinuities that are considered harmful to the end use of the product
• B. To give the technician a tool for determining exact discontinuity size
• C. To provide assurance that all discontinuities smaller than a certain specified reference reflector are capable of being detected by the test
• D. To provide a standard reflector which exactly simulates natural discontinuities of a critical size