the peaks of a mountain range, acting like rocks in a streambed, produce ripples in the air flowing over then; the resulting flow pattern, with crests and troughs that remail stationary although the air that forms them is moving rapidly , are known as "standing waves."
A crests and troughs that remail stationary although the air that forms them is moving rapidly , are
B crests and troughs that remail stationary although they are formed by rapidly moving air, are , are
C crests and troughs that remail stationary although the air that forms them is moving rapidly , is
D stationary crests and troughs although the air that forms them is moving rapidly, are
E stationary crests and troughs although they are formed by rapidly moving air, is
请问,根据曼哈顿:incorrect use of 'although' in the subordinate clause: 'although' has to separate a CLAUSE (with a verb) from another CLAUSE (with a verb). 'Stationary crests and troughs' doesn't have a verb. although是用来连接两个句子,所以E可以被排除,但是C选项中,although前面也不是带动词的句子啊?