正解:A
Explanation
Isolating the affected system is the first step in the incident response process, as it helps to contain the attack, prevent further damage, and preserve the evidence for analysis. Isolating the system can be done by disconnecting it from the network, blocking the malicious traffic, or applying quarantine rules.
References = CISM Review Manual 2022, page 3121; CISM Exam Content Outline, Domain 4, Task 4.22; Cybersecurity Incident Response Exercise Guidance3