Final answer:
The Biological Indicator (BI) should be placed inside the rigid sterilization container, typically in the location most challenging for the sterilizing agent to reach.
Step-by-step explanation:
When testing rigid sterilization containers, the Biological Indicator (BI) should be placed inside the container. The placement of BIs is critical for ensuring that sterilization processes are effective. BIs are generally positioned within the container, in locations where it is most challenging for the sterilizing agent to reach, to verify the effectiveness of the sterilization process. This often means placing the BI in the middle of the container, but the specific position can vary depending on the container's design and the load. For accurate results, it is important to follow the manufacturer-specified protocols when placing BIs during sterilization testing.