CompTIA CySA+ CS0-003 explicitly lists "proprietary systems" as an inhibitor to remediation (i.e., a common obstacle that can delay or block patching/remediation).
Why D (Proprietary systems) is most likely to cause obstacles:
* Proprietary systems often require vendor-provided patches, may have restricted modification, and can create delays due to vendor response time and dependencies on vendor updates. The Secbay Press guide explains that proprietary systems can be challenging due to "restricted access, dependencies on vendor updates, and potential delays in patching."
* The Sybex Study Guide also describes that proprietary systems may not have patches available quickly (or at all), and that vendor support requirements can conflict with vulnerability management needs:
Exact extract (Sybex Study Guide): "Proprietary systems... may not have patches available or may have specific requirements placed on them by vendors... creating a conflict between vulnerability management policies and functional or business requirements." Why the other options are less "most likely" here:
* A (Not meeting an SLA) is typically an outcome (a consequence) rather than the obstacle itself. The inhibitor is the SLA constraints, not "not meeting it." CompTIA objectives list SLA as an inhibitor, not
"not meeting an SLA."
* B (Patch prioritization) is a normal vulnerability management activity, not typically categorized as an inhibitor/obstacle in the CS0-003 inhibitor list.
* C (Organizational governance) is also an inhibitor (bureaucracy/change control can slow remediation), but proprietary systems are often the most "hard-blocking" because you may be unable to patch without vendor action/support. Both are valid inhibitors, but "most likely" in practice (especially in exam framing) commonly points to vendor-controlled/proprietary constraints.
References (CompTIA CySA+ CS0-003 documents / study guides used):
* CompTIA CS0-003 Exam Objectives v4.0: "Inhibitors to remediation" includes proprietary systems
* Secbay Press CS0-003: Proprietary systems create remediation challenges due to vendor dependency and patch delays
* Sybex CS0-003 Study Guide: proprietary systems may restrict patching and vendor support requirements can block remediation