正解:D
The best first step is to evaluate and prioritize the risk to determine the appropriate treatment strategy before implementing mitigation.
"Once risks are identified, they should be evaluated and prioritized to determine the best response (mitigation, transfer, acceptance, or avoidance)."
- CISM Review Manual 15th Edition, Chapter 2: Risk Management, Section: Risk Treatment* ISACA practice questions confirm the need for evaluation and prioritization before taking further action.