Section 11.6.3 of API 580 defines iso-risk lines:
"An ISO-risk line represents a constant risk level... All items that fall on or very near the ISO-risk line are roughly equivalent in their level of risk." This confirms that iso-risk lines plot constant risk across varying combinations of probability and consequence.
Reference: API 580, 2nd Edition (2016), Section 11.6.3 - Risk Plots

According to API 580, Section 4.3:
"RBI as a risk-based approach focuses attention specifically on the equipment and associated damage mechanisms representing the most risk to the facility." This confirms that the correct focus of RBI is on the equipment and the damage mechanisms that pose the greatest risk-making Option A correct. Other options are examples of traditional inspection strategies, not the defining focus of RBI.
Reference: API 580, 2nd Edition (2016), Section 4.3

As defined in API 580, Section 3.1.59:
"Risk evaluation: The process used to compare the estimated risk against given risk criteria to determine the significance of the risk." This follows from the broader risk assessment process where risk identification and analysis occur first, followed by risk evaluation.
Reference: API 580, 2nd Edition (2016), Section 3.1.59

"Integrity Operating Windows (IOWs)" are described in API 580 and API RP 584. Process parameters such as temperature, pressure, and fluid velocity are IOWs.
From API 580 Section 15.2.6:
"Operations personnel are responsible for verifying that the facility/equipment is being operated within the parameters set out in the process operating window," which includes fluid velocity.
Materials of construction and vibration frequency are not typical IOWs.
Reference: API 580, 2nd Edition (2016), Section 15.2.6

According to Section 5.2 of API 580:
"One objective of RBI is to determine what incident could occur (consequence) in the event of an equipment failure and how likely (probability) it is that the incident could happen." This is the foundational purpose of RBI: to determine both the likelihood and the consequence of a potential failure event, with specific emphasis on loss of containment.
While B, C, and D are partially true and are part of the broader RBI process, option A captures the exact phrasing and complete intent as outlined in the standard.
Reference: API 580, 2nd Edition (2016), Section 5.2