A technician is replacing the power supply in a computer.

When replacing a power supply in a computer, wearing an antistatic wrist strap is crucial to prevent static electricity from damaging the computer components. Static electricity can easily damage sensitive electronic components within the computer; therefore, using an antistatic wrist strap helps to ground the technician, mitigating the risk of electrostatic discharge. The other options provide general safety but do not address the primary concern of electrostatic discharge in this context.