FlexVPN supports IKEv2 -> Answer A is not correct.
DMVPN supports both IKEv1 & IKEv2 -> Answer B is not correct.
FlexVPN support multiple SAs -> Answer D is not correct.

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Other features are dependent on SSL Decryption functionality, which requires the Cisco Umbrella root certificate. Having the SSL Decryption feature improves: Custom URL Blocking-Required to block the HTTPS version of a URL. ... Umbrella's Block Page and Block Page Bypass features present an SSL certificate to browsers that make connections to HTTPS sites. This SSL certificate matches the requested site but will be signed by the Cisco Umbrella certificate authority (CA). If the CA is not trusted by your browser, an error page may be displayed. Typical errors include "The security certificate presented by this website was not issued by a trusted certificate authority" (Internet Explorer), "The site's security certificate is not trusted!" (Google Chrome) or "This Connection is Untrusted" (Mozilla Firefox). Although the error page is expected, the message displayed can be confusing and you may wish to prevent it from appearing. To avoid these error pages, install the Cisco Umbrella root certificate into your browser or the browsers of your users-if you're a network admin. Reference: https://docs.umbrella.com/deployment-umbrella/docs/rebrand-cisco-certificate-import-information certificate. Having the SSL Decryption feature improves:
Custom URL Blocking-Required to block the HTTPS version of a URL.
...
Umbrella's Block Page and Block Page Bypass features present an SSL certificate to browsers that make connections to HTTPS sites. This SSL certificate matches the requested site but will be signed by the Cisco Umbrella certificate authority (CA). If the CA is not trusted by your browser, an error page may be displayed.
Typical errors include "The security certificate presented by this website was not issued by a trusted certificate authority" (Internet Explorer), "The site's security certificate is not trusted!" (Google Chrome) or "This Connection is Untrusted" (Mozilla Firefox). Although the error page is expected, the message displayed can be confusing and you may wish to prevent it from appearing.
To avoid these error pages, install the Cisco Umbrella root certificate into your browser or the browsers of your users-if you're a network admin.
Other features are dependent on SSL Decryption functionality, which requires the Cisco Umbrella root certificate. Having the SSL Decryption feature improves: Custom URL Blocking-Required to block the HTTPS version of a URL. ... Umbrella's Block Page and Block Page Bypass features present an SSL certificate to browsers that make connections to HTTPS sites. This SSL certificate matches the requested site but will be signed by the Cisco Umbrella certificate authority (CA). If the CA is not trusted by your browser, an error page may be displayed. Typical errors include "The security certificate presented by this website was not issued by a trusted certificate authority" (Internet Explorer), "The site's security certificate is not trusted!" (Google Chrome) or "This Connection is Untrusted" (Mozilla Firefox). Although the error page is expected, the message displayed can be confusing and you may wish to prevent it from appearing. To avoid these error pages, install the Cisco Umbrella root certificate into your browser or the browsers of your users-if you're a network admin. Reference: https://docs.umbrella.com/deployment-umbrella/docs/rebrand-cisco-certificate-import-information