Which components can be touched to minimize the risk of ESD if a field kit is unavailable?

Touching the bare metal on the inside of the chassis and the power supply case is the best practice for minimizing the risk of Electrostatic Discharge (ESD). When you come into contact with these metal components, it helps to discharge any static electricity that may have built up on your body, effectively grounding you. This action reduces the likelihood of ESD damaging sensitive electronic components, which can occur during installation or maintenance tasks.

The other options do not provide the same level of ESD protection. For instance, touching the motherboard and RAM may present a risk rather than minimize it, as these components are sensitive to ESD. Copper wiring does conduct electricity but is not a recommended grounding method due to potential risks of short circuits and other electrical safety issues. Lastly, the plastic casing of the chassis does not conduct electricity and therefore does not offer a grounding effect to dissipate static charge.