During an overnight maintenance window you must replace a failed DIMM in a rack-mounted application server. The host is already powered down and its AC cords have been removed from the PDU. After you put on a wired anti-static wrist strap, which action with the strap will provide continuous electrostatic-discharge protection while you handle the memory module inside the chassis?
Clip the strap's lead to an unpainted chassis screw on the server after the power cords have been unplugged.
Attach the strap to the outside of the static-shielding bag that contains the replacement DIMM.
Plug the strap into a grounding lug on the facility UPS while leaving the server connected to mains power.
Snap the strap onto the powder-coated rack rail that supports the server.
The other choices do not create a safe, reliable path:
The outside of a shielding bag is deliberately conductive but is not referenced to the server, so charge can still jump to the DIMM.
Powder-coated rack rails are insulated; the paint prevents an electrical connection.
Connecting the strap to a facility UPS while the server remains on mains power bonds the technician to a different ground and violates ESD and electrical-safety best practice.