ANSWER

A.　Sight information such as the expressions of the face

According to the American psychologist, the famous laboratory finding by the Albert Murray, the language information such as hearing information 38% of sight information 55% of expressions of the face, quality of voice or tones, the contents of the story does it with 7%.

In online chat rooms we don't have sight information such as the expressions of the face.
We are able to comunicate only the contents of the story.