Which of the following is the MOST appropriate action during the containment phase of a...

The containment phase focuses on limiting the scope of the incident. Isolating affected systems immediately helps prevent propagation and further compromise.

“During the containment phase, isolating compromised systems is a key tactic to minimize further impact and enable safe recovery.”

— CISM Review Manual 15th Edition, Chapter 4: Incident Response Life Cycle, Section: Containment Strategies*