Business Email Compromise (BEC) is a targeted phishing attack in which attackers impersonate executives or high-ranking officials (such as a CEO) to manipulate employees into transferring money or providing sensitive data. Since the request is coming from the CEO's corporate email (possibly spoofed or compromised), this is a classic example of BEC.
Phishing (B) is a broader term but typically involves mass fraudulent emails rather than targeted executive impersonation.
Brand impersonation (C) involves faking a company's identity (e.g., fake PayPal emails).
Pretexting (D) involves social engineering tactics but does not necessarily involve email compromise.
Reference:
CompTIA Security+ SY0-701 Official Study Guide, Threats, Vulnerabilities, and Mitigations domain.