Five year testing of safeties for types A, B, C car safeties must be tested at what conditions?

The correct choice highlights that the five-year testing of safeties for types A, B, and C car safeties must be conducted at the rated speed and rated load. This is important because the rated speed and rated load represent the operational parameters for which the elevator system is designed.

Testing under these specific conditions ensures that the safeties function correctly within the parameters that the elevator will typically encounter during its operation. It reflects the elevator's normal working environment, providing a realistic assessment of safety device performance. Ensuring the safety mechanisms work properly at these conditions is fundamental to meeting safety regulations and ensuring the reliability of the elevator system.

Test conditions that involve maximum speeds or loads might not accurately reflect everyday operations, while minimum speeds or loads wouldn't provide a true measure of the safety features since elevators rarely operate under those circumstances. Similarly, testing at average speeds or average loads lacks the specificity required for regulatory compliance regarding safety mechanisms. Thus, conducting tests at intended rated conditions is critical for confirming that the safety measures will perform as required in real-world applications.