Which of These Would Need to Occur for a Disease

Multiple Choice

Which of these would need to occur for a disease to be considered communicable?

A) A susceptible host encounters an infectious agent.
B) An infectious agent colonizes a host.
C) An infectious agent colonizes a host and can be transmitted to another host.
D) An infectious agent causes damage to the host.
E) An infectious agent causes damage to the host and can be transmitted to another host.