Question

what do all chain hoists use to lift heavy loads?
sprocket set
anchorage slide
hook retainer
gear system

Explanation:

Chain hoists rely on a gear system to lift heavy loads. The gear system allows for mechanical advantage, making it easier to lift heavy objects. A sprocket set is part of a chain - related mechanism but not the core for lifting heavy loads in the context of chain hoists. An anchorage slide is more about securing in place rather than lifting. A hook retainer is for holding the hook, not for the lifting action itself.

Answer:

gear system