Why Are Face-To-Face Meetings Between People Usually Much More Meaningful

Why are face-to-face meetings between people usually much more meaningful than telephone or written exchanges?

A) Face-to-face meetings allow people to speak more precisely. If something is misunderstood it can be corrected or repeated.
B) Face-to-face meetings allow people to ignore the emotional content of each other's message and focus on facts. This makes for a more meaningful exchange.
C) Face-to-face meetings allow participants to observe nonverbal communication. This helps people assess each other's emotional state as well as the message's factual content.
D) Face-to-face meetings allow people to speak more openly. People tend to fear that written or telephone exchanges are being recorded, so they aren't as truthful or candid.