Fire-resistant safes must pass which type of test?

Fire-resistant safes are designed to protect their contents from fire, and as such, they must undergo specific testing methods to ensure their effectiveness in real-world scenarios. Fire exposure testing is the primary focus, as these safes need to withstand high temperatures without compromising the integrity of the contents inside.

In addition to fire exposure, these safes are also subjected to impact tests to evaluate their durability against physical damage that could occur during a fire, such as falling debris or being struck by heavy objects. Explosion tests may also be relevant, particularly for safes designed to protect sensitive materials that could be affected by changes in pressure or sudden impacts from an explosion.

Therefore, the necessity for fire-resistant safes to pass a comprehensive range of tests, including fire exposure, impact, and explosion, ensures that they provide maximum protection under various adverse conditions. This multi-faceted approach to testing affirms the reliability and thoroughness in the safe's design and functionality, making "All of the above" the correct answer.