Adversary emulation simulates specific advanced persistent threat (APT) behaviors and techniques to test an organization's security posture. In SecurityX CAS-005, this is part of red-teaming and purple-teaming strategies for realistic resilience testing. Reliability factors (B) relate to operational uptime, not threat SIMULATION. Honeypots (C) attract attackers but do not directly emulate specific adversaries. Internal reconnaissance (D) is one phase of an attack SIMULATION, not the full emulation of advanced threat actors.