This question fits the Process domain because it concerns risk response execution, issue handling, and integrated change control. PMI risk guidance explains that risk response planning develops options and actions for identified risks, but if the planned response is no longer the best option, the project manager should use formal project control mechanisms before changing the agreed approach. A different response may affect scope, cost, schedule, or management plans, so it should be processed formally rather than implemented informally.
Option A is too rigid because PMI expects professional judgment, not blind adherence. Option C escalates too quickly and skips formal change control. Option D is excessive because the issue concerns one response, not the need to reevaluate all registered responses. The strongest PMP-aligned action is to submit a change request for the new issue response. That preserves governance, documents the rationale, and ensures the revised response is reviewed and approved appropriately before implementation. This reflects disciplined issue management and change control within the project management process.