what do all chain hoists use to lift heavy loads?\nsprocket set\nanchorage slide\ngear system\nhook retainer

Brief Explanations:

Chain hoists use a sprocket set to engage with the chain for lifting heavy - loads. The sprocket set helps in winding and unwinding the chain to raise or lower the load. An anchorage slide is for securing the hoist, a gear system is more general and not the key component like the sprocket set for chain - chain interaction, and a hook retainer is for keeping the hook in place, not for the lifting mechanism itself.

Answer:

A. sprocket set