Which of the following is a valid electrical safety precaution when working on a computer or display with exposed, potentially energized parts?

A.
Use only metal screw drivers or fingers as needed to connect or disconnect cables.

B.
Always wear an ESD wrist or heel strap when working on plugged in systems.

C.
Be very careful handling the logic board or power supply while the computer is plugged in.

D.
Remove rings, watches, necklaces, metal-rimmed eyewear and other metallic articles before working on the computer.

Explanation:
Rings, watches, necklaces or any metallic wearables should be removed because metal will disturb the inner circuitry and the static charge will transfer to the
sensitive parts of the computer. Reference: http://mdex-nn.ru/uploads/imac12.pdf (page 3, electrical safety precautions