According to the exhibit, the network topology and SSID settings show that FortiGate is configured to use an external captive portal hosted on FortiAuthenticator, which is connected to a Windows AD server for user authentication. However, wireless users are not able to see the captive portal login page, which means that they are not redirected to the external captive portal URL. Therefore, option B is true because adding the FortiAuthenticator and WindowsAD address objects as exempt destinations services will allow the wireless users to access the external captive portal URL without being blocked by the firewall policy.

Explanation
According to the exhibit, the wireless guest users are getting a certificate error while loading the captive portal login page. This means that the browser cannot verify the identity of the server that is hosting the login page.
Therefore, option A is true because the external server FQDN is incorrect, which means that it does not match the common name or subject alternative name of the server certificate. Option B is also true because the wireless user's browser is missing a CA certificate, which means that it does not have the root or intermediate certificate that issued the server certificate. Option C is false because the FortiGate authentication interface address is using HTTPS, which is a secure protocol that encrypts the communication between the browser and the server. Option D is false because the user address is not in DDNS form, which is not related to the certificate error.