Final answer:
The correct meaning of HVSACO is 3) High Voltage Special Access Control Order.
Step-by-step explanation:
This abbreviation is related to a control order that is specific to high voltage systems or equipment which requires special access. It could be used to designate certain protocols or procedures that need to be followed when dealing with high voltage equipment or systems.
For example, in an industrial setting, high voltage equipment may be placed under a special access control order, meaning that only authorized personnel with the appropriate training and safety procedures can access or work on the equipment. This is done to ensure the safety of both the workers and the equipment itself. So, the most appropriate meaning for HVSACO in the given options is 3) High Voltage Special Access Control Order.