Where must communications be encrypted with TLS?

In a Mobile and Remote Access deployment, where must communications be encrypted with TLS?
A. Cisco Expressway-E and endpoints outside the enterprise
B. Cisco Expressway-C, Cisco Unified Communications Manager, and IM&P
C. Cisco Expressway-C, Cisco Expressway-E, and Cisco Unified Communications Manager
D. Cisco Expressway-C, Cisco Expressway-E, and endpoints outside the enterprise