Organizations must manage risks to a level that is acceptable for their business model, goals and objectives. A zero-level approach may be costly and not provide the effective benefit of additional revenue to the organization. Long-term maintenance of this approach may not be cost effective. Risks vary as business models, geography, and regulatory- and operational processes change. Insurance covers only a small portion of risks and requires that the organization have certain operational controls in place.

Explanation
The best way to identify the risk associated with a social engineering attack is to test user knowledge of information security practices. Social engineering is a type of attack that exploits human psychology and behavior to manipulate, deceive, or influence users into divulging sensitive information, granting unauthorized access, or performing malicious actions. Therefore, user knowledge of information security practices is a key factor that affects the likelihood and impact of a social engineering attack. By testing user knowledge of information security practices, such as through quizzes, surveys, or simulated attacks, the information security manager can measure the level of awareness, understanding, and compliance of the users, and identify the gaps, weaknesses, or vulnerabilities that need to be addressed.
Monitoring the intrusion detection system (IDS) (A) is a possible way to detect a social engineering attack, but not to identify the risk associated with it. An IDS is a system that monitors network or system activities and alerts or responds to any suspicious or malicious events. However, an IDS may not be able to prevent or recognize all types of social engineering attacks, especially those that rely on human interaction, such as phishing, vishing, or baiting. Moreover, monitoring the IDS is a reactive rather than proactive approach, as it only reveals the occurrence or consequences of a social engineering attack, not the potential or likelihood of it.
Reviewing single sign-on (SSO) authentication lags (B) is not a relevant way to identify the risk associated with a social engineering attack. SSO is a method of authentication that allows users to access multiple applications or systems with one set of credentials. Authentication lags are delays or failures in the authentication process that may affect the user experience or performance. However, authentication lags are not directly related to social engineering attacks, as they do not indicate the user's knowledge of information security practices, nor the attacker's attempts or success in compromising the user's credentials or access.
Performing a business risk assessment of the email filtering system (D) is also not a relevant way to identify the risk associated with a social engineering attack. An email filtering system is a system that scans, filters, and blocks incoming or outgoing emails based on predefined rules or criteria, such as spam, viruses, or phishing. A business risk assessment is a process that evaluates the potential threats, vulnerabilities, and impacts to the organization's business objectives, processes, and assets. However, performing a business risk assessment of the email filtering system does not address the risk associated with a social engineering attack, as it only focuses on the technical aspects and performance of the system, not the human factors and behavior of the users.
References = CISM Review Manual, 16th Edition, Chapter 2: Information Risk Management, Section: Risk Identification, Subsection: Threat Identification, page 87-881