A、Spring. B、Winter. C、Autumn. D、Summer. D 对话中谈到很多人认为加拿大的夏季最适合娱乐和放松，因此答案是D。

A: How is Canada’s climate? Is it intolerably cold in winter?
B: People tend to think that as Canada is a northern country, its winters must be harsh and long. But contrary to the popular belief, on the whole, Canada is a very sunny land with a distinctive change of seasons. Of course, since Canada is such a vast country, its climate varies greatly from region to region.
A: Really? That sounds amazing to me.
B: Yes, when talking about Canada’s climate, people usually divide it into six climatic regions.
A: In general, how are the four seasons divided?
B: Generally speaking, spring begins in mid March and ends in mid May. It is regarded as a transitional time in Canada. Summer lasts for about four months. Autumn is the shortest season, less than about three months. Winter is the longest season in most of Canada.
A: Is summer in Canada very hot?
B: No. The summer in Canada is warm and sunny. For most people, it is the best season for fun and relaxation.
A: How about autumn?
B: Autumn is very beautiful, though it is brief.
A: Is winter in Canada terribly cold?
B: Well, the winter in Canada is indeed very long, but it is not gloomy because there is much sunshine. So many people enjoy skiing and skating in winter.