Which four requirements are mandatory to enable a mixed mode Cisco Unified CM cluster?

Which four requirements are mandatory to enable a mixed mode Cisco Unified CM cluster? (Choose four.)
A. Cisco CTL Provider Service activated and enabled
B. Cisco Certificate Authority Proxy Function activated and enabled
C. Cisco Trust Verification activated and enabled
D. Cisco CTL client
E. a minimum of one USB e-token
F. a minimum of two USB e-token
G. a minimum of one soft e-token