Question

which of the following characteristics must be present on all hard hats?
electrical shock resistance
shielding against splashes
a suspension system inside
a mounted work light

Explanation:

Hard hats are safety gear for head protection. A suspension system inside is crucial as it distributes impact forces. Electrical shock resistance (for specific electrical - work hats only), shielding against splashes (more for face - shields in some cases), and a mounted work light (an added - on feature, not mandatory) are not universal requirements like the suspension system.

Answer:

A suspension system inside