Valerie knows that a system in her environment has been compromised and wants to take immediate action. Which of the following options should she select if she is worried about the system impacting other hosts on the network?

Isolating the system is the best option for Valerie to select until she can investigate the system. Isolation will prevent the system from impacting other systems and will also prevent attackers from getting to it. Antimalware and patching are useful options further into the investigation and response process. Changing default passwords and checking for unexpected user accounts is a good practice but won't help protect other systems if the system is compromised.