What should the architect change in the SAML action to resolve this issue?

Scenario: A Citrix Architect has deployed an authentication setup with a ShareFile load-balancing virtual server. The NetScaler is configured as the Service Provider and Portalguard server is utilized as the SAML Identity Provider. While performing the functional testing, the architect finds that after the users enter their credentials on the logon page provided by Portalguard, they get redirected back to the Netscaler Gateway page at uri /cgi/samlauth/ and receive the following error.

The events in the /var/log/ns.log at the time of this issue are as follows:

What should the architect change in the SAML action to resolve this issue?
A . Signature Algorithm to SHA 256
B . The Digest Method to SHA 256
C . The Digest Method to SHA 1
D . Signature Algorithm to SHA 1

Answer: C