(单选题)

What does "vicious circle" mean in the fourth para. according to the passage? ( )

A.People are constantly confronted with similar problem.

B.One problem that cannot be solved once and for all.

C.An increasingly serious problem without effective action.

D.One trouble leads to another that aggravate the first.

参考答案：D

参考解析：

含义题。定位第四段，It's also a possibility, according to the research team, that seasonal-depression symptoms will push individuals to start eating more sweets. This will, in turn, only create a vicious cycle.研究小组表示，季节性抑郁症状也有可能促使人们开始吃更多的甜食。这反过来只会造成恶性循环。A项：人们经常遇到类似的问题；B项：一个不能一劳永逸地解决的问题；C项：没有有效行动的日益严重的问题；D项：一个问题导致另一个问题而使前者恶化。故本题正确答案选D。

知识点：细节题英语阅读理解通用英语