A channel of communication is a way to relay information using body language.
a verbal cue.
a way that messages are relayed,
a way to achieve effective communication,

A channel of communication is a way that messages are relayed.

Explanation:

Communication channels are the means used to convey a message, facilitating the communication process.

In the communication process, an emitter uses the most appropriate communication channel to transmit a message to the receiver.  This channel is a support, and is the tool used to transmit this messages.

Examples:

The telephone, internet, written press, television and radio are other examples of communication channels.

The other options are not correct because:

a lack of sleep can affect body weight. two hormones in the body, leptin and ghrelin, control feelings of hunger and satiety, or fullness.

explanation:

what test are you taking