In recent years many mainland residents have rushed to Hong Kong to buy baby milk powder

问题补充：

In recent years, many mainland residents have rushed to Hong Kong to buy baby milk powder due to their about its quality.

A. anxiety

B. curiosity

C. generosity

D. attention

答案：

(答案→)A. anxiety

B. curiosity

C. generosity

D. attention

解析：A 考察名词辨析。句义：近年来大陆居民奔赴香港购买奶粉，因为他们担心奶粉的质量。Anxiety担心，符合题意。故A正确。Curiosity因为“好奇”；generosity慷慨；attention注意。均与语境不符。