Step 1: Identify channels.
Communication involves encoding (speaking/writing), decoding (listening/reading), and non-verbal cues (posture, gaze, gestures, facial affect).
Step 2: Apply to options.
Listening (receiver skill), Speaking (sender skill), and Body language (non-verbal channel) are all integral.
Step 3: Conclude.
Hence the comprehensive choice is All of these.
\[
\boxed{\text{Option D}}
\]