the extreme levels of air pollution, city authorities have started to take measures to quickly reduce pollution levels and protect city dwellers.
A. In spite of
B. As well as
C. In response to
D. By means of
网友回答
A. In spite of
B. As well as
(答案→)C. In response to
D. By means of
解析：考查介词短语辨析。句意：针对空气污染的极端水平，市政府开始采取措施，迅速降低污染水平和保护城市居民。in spite of尽管；as well as而且，还；in response to针对，应对；by means of以……的方式。故C正确。