Which of the following must be verified before conducting a foam solution-concentrate test?

Before conducting a foam solution-concentrate test, it is essential to verify that the apparatus's water and foam systems are operational. This is critical because the effectiveness of the foam in suppressing fires relies on the proper mixing and application of water and foam concentrate. If either system is not functioning correctly, the test could yield inaccurate results, potentially compromising safety measures during an emergency situation.

Operational verification ensures that the equipment can deliver the foam solution as intended, achieving the correct mixing ratio and distribution needed for effective fire suppression. This step is non-negotiable because without proper operational systems in place, attempts to conduct the test could not only fail but also lead to an ineffective response in real-world scenarios.