Concept:Intonation refers to the pattern of pitch changes in speech that can affect meaning or emotion.
Explanation:Intonation is the variation in pitch while speaking.
Pitch means how high or low the voice sounds.
For example, a rising pitch at the end of a sentence often indicates a question.
A falling pitch can show a statement or finality.
Combinations like rising-falling or falling-rising also occur.
Without intonation, speech would be flat and monotonous.
Thus, intonation is directly about changes in pitch, not organ, sound in general, or air.
Answer:Option D: pitch