What is the reason for the Critical Problem notification in this SmartView Monitor example?

What is the reason for the Critical Problem notification in this SmartView Monitor example?

A.
Active real memory shortage on the Gateway

B.
No Security Policy installed on the Security Gateway

C.
Version mismatch between the SmartCenter Server and Security Gateway

D.
Time not synchronized between the SmartCenter Server and Security Gateway

E.
No Secure Internal Communications established between the SmartCenter Server and Security Gateway