What three changes have occurred in modern networks that require enhanced security?

What three changes have occurred in modern networks that require enhanced security? (Choose three.)
A. Modern networks utilize a common set of widely known and open protocols.
B. The use of common operating systems on smart phones such as Apple iOS and Android has provided attackers with simpler means to instigate targeted attacks.
C. Fault tolerance and backup systems provide threat actors easy access to system resources and data.
D. The global connectivity of the Internet provides more opportunities for threat actors to connect to information systems.
E. The increased complexity of operating systems and application software has made it more difficult to ensure security across all systems.