单选题 Which of the following italicized phrases indicates purpose?

A、 She said it for fun, but others took her seriously.
B、 For all its effort, the team didn't win the match.
C、 Linda has worked for the firm for twenty years.
D、 He set out for Beijing yesterday.

【正确答案】 A

【答案解析】[考点] 考查介词for构成的短语的用法。