What is the role of a firewall in an enterprise network?

Answer C is the technically correct selection. A firewall decides which packets may cross between networks or security zones. Enterprise firewalls enforce policy between trusted and untrusted segments using rules, state, applications, users, or zones depending on platform capability. This aligns with Cisco CCNA 200-301 v1.1 because the exam blueprint requires engineers to recognize operational behaviour from configuration symptoms and topology requirements. It does not simply forward all unauthorized packets or explicitly deny every packet regardless of policy. Treat the distractors carefully: most are real Cisco terms, but they solve a different problem or operate at a different layer. The selected answer is the one that would be used by an engineer on the device or in the design to produce the outcome stated in the question.