What is the most likely reason for this situation?

Refer to the exhibit.

FortiGate is configured for firewall authentication. When attempting to access an external website, the user is not presented with a login prompt.

What is the most likely reason for this situation?
A . No matching user account exists for this user.
B . The user is using a guest account profile.
C . The user was authenticated using passive authentication.
D . The user is using a super admin account.

Answer: C

Explanation:

The most likely reason for a user not being presented with a login prompt when attempting to access an external website in a FortiGate firewall authentication scenario is:

C. The user was authenticated using passive authentication.

Passive authentication allows the FortiGate to authenticate users transparently without presenting them with a login prompt. This often involves the use of authentication methods such as Captive Portal or single sign-on (SSO) techniques where users are authenticated based on their network activity without actively entering credentials.

Options A, B, and D are less likely to cause the absence of a login prompt in this context: A is less likely because if there was no matching user account, it would typically result in an authentication prompt.

B is less likely unless the guest account profile specifically has a passive authentication mechanism.

D is less likely because super admin accounts are typically not subject to transparent or passive authentication mechanisms.

So, the most likely reason is C.