单选题
If you are like most people, your intelligence (智力) is different in different seasons. You are probably a lot cleverer in spring than you are at any other time of the year. A famous scientist, Ellsworth Huntington (1876-1947), concluded from other men's work and his own on peoples (民族) in different climates that climate and temperature have a definite (明确的) effect on our mental (智力的) abilities.
He found that cool weather is much more favorable for creative thinking than summer heat. This does not mean that all people are less clever in summer than they are during the rest of the year. It does mean, however, that the mental abilities of large numbers of people tend to (倾向于) be lower in summer.
Spring appears to be the best period of the year for thinking. One reason may be that in the spring man's mental abilities are affected by the same factors that bring about great changes in all nature (万物).
Fall is the next-best season, then winter. As for summer, it seems to be a good time to take a long vacation free from thinking!