[单项选择]

Researchers produced evidence to support what most of us already knew--that a cup of tea is the answer to any crisis.
Dr. Malcolm Cross, a psychologist at City University London, tested the anxiety levels of a group of people following a (51) situation and revealed that even a single cup of tea has a (52) calming effect. His team gave 42 volunteers a mental arithmetic exam and (53) offered half of them a cup of tea and the other half a glass of water. The water group’s anxiety levels soared (54) 25 percent compared to before the task, (55) the tea group actually reported a four percent reduction in anxiety--despite the difficult test, they were more relaxed than when they started.
According to a survey carried out for the research, 68 percent of Britons (56) tea in a dilemma, making it the nation’s most common response to trouble of (57) kind. About 60 percent said the promise of comfort an
A. on 
B. in 
C. by 
D. at

Researchers produced evidence to support what most of us already knew--that a cup of tea is the answer to any crisis.
Dr. Malcolm Cross, a psychologist at City University London, tested the anxiety levels of a group of people following a (51) situation and revealed that even a single cup of tea has a (52) calming effect. His team gave 42 volunteers a mental arithmetic exam and (53) offered half of them a cup of tea and the other half a glass of water. The water group’s anxiety levels soared (54) 25 percent compared to before the task, (55) the tea group actually reported a four percent reduction in anxiety--despite the difficult test, they were more relaxed than when they started.
According to a survey carried out for the research, 68 percent of Britons (56) tea in a dilemma, making it the nation’s most common response to trouble of (57) kind. About 60 percent said the promise of comfort an
A. light-hearted 
B. serious 
C. comfortable 
D. stressful