Final answer:
A. in the most challenging area of the load. Biological indicators should be placed in the most challenging area of the load in steam sterilization.
Step-by-step explanation:
In steam sterilization, biological indicators should be placed in the most challenging area of the load. This is because biological indicators, such as endospores of heat-resistant bacteria, are used to validate the effectiveness of the sterilization process. By placing the biological indicators in the most challenging area, we can ensure that the entire load has been properly sterilized and that any potential sterilization failures are detected.