It follows from the weak axiom of revealed preference that if a consumer chooses x when he could afford y and chooses y when he could afford x； then his income must have changed between the two observations.。

It follows from the weak axiom of revealed preference that if a consumer chooses x when he could afford y and chooses y when he could afford x； then his income must have changed between the two observations.。
A.正确
B.错误
正确答案：错误