The screenshot shows a login form where the user coder@viewer attempts to log in, and the application responds with "User does not exist." Let’s evaluate the statements:

Option A ("The application is vulnerable to username enumeration"): Correct. Username enumeration occurs when an application reveals whether a username exists in the system, often through distinct error messages. Here, the message "User does not exist" for coder@viewer directly indicates that the username is invalid, allowing an attacker to enumerate valid usernames by testing different inputs and observing the responses (e.g., "Invalid password" for existing users vs. "User does not exist"). Best practice is to use generic error messages like "Invalid username or password" to prevent enumeration.

Option B ("The application is vulnerable to brute-force attacks"): Incorrect. There’s no evidence in the screenshot of a lack of brute-force protections (e.g., rate limiting, account lockout). Brute-force vulnerability would require additional context, such as no CAPTCHA or no lockout mechanism, which is not shown.

Option C ("The application does not enforce a strong password policy"): Incorrect. The screenshot does not provide information about password requirements (e.g., length, complexity), so we cannot conclude whether a strong password policy is enforced.

Option D ("None of the above"): Incorrect, as A is true.

The correct answer is A, aligning with the CAP syllabus under "Username Enumeration" and "Authentication Security."References: SecOps Group CAP Documents - "Authentication Best Practices," "Enumeration Attacks," and "OWASP Authentication Cheat Sheet" sections.