Frank was determined not to let Dorothy know he was upset, so he avoided looking at her and only spoke in one-word responses, but Dorothy knew immediately something was wrong. This demonstrates the _________ of the communication process.

Communication is considered as inevitable for us as human beings because when people are involved in a particular situation, they are in some sort of communication with the others present there even if they are verbally not speaking something. This could be non-verbal as well through body language, gestures, and even ignorance reflects communication and thus, for humans communication is inevitable.

In the given situation, 'inevitability' of the communication process is reflected as even if Frank chose to not let Dorothy know about his disturbed state, his non-verbal cues like intonation reflected in his one-word replies and his avoidance made Dorothy understand that something is wrong. Therefore, it reflects the inevitability of communication as a process as even if Frank didn't reveal anything directly to Dorothy but his non-verbal actions communicated his message.