单项选择题

A.正确,尽管变量var2定义了两次,但程序自动将它们看成一个变量;
B.正确,前面出现的变量var2有效期仅在if中,不会与后面的变量var2重叠;
C.错误,if块中的变量var2有效期从这里直到函数结束,因此会出现变量重叠;
D.错误,不管变量在哪里定义,它们都会在函数入口处初始化,因此会出现变量重叠;
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