Sentence Correction (SC) | Re: QOTD: The peaks of a mountain range, acting like

The peaks of a mountain range, acting like rocks in a streambed, produce ripples in the air flowing over them; the resulting flow pattern, withcrests and toughs that remain stationary although the air that forms them is moving rapidly, are known as "standing waves."

(A) crests and toughs that remain stationary although the air that forms them