The author's main purpose in writing the last paragraph of the passage was to ______ . A.explain how cold viruses are transmitted B.prove that a poor diet causes colds C.discuss the relationship between income and frequency of colds D.analyze the distribution of income among the people in the study
A.A.explain B.prove C.discuss D.analyze
【参考答案】
C 解析：细节题型见第三段：研究还发现经济问题也扮演了一个重要角色。据报道随着家庭收入的增加，患感冒的次数会减少......