下列函数能构成复合函数是（  ）

A、<p><img src="http://oapi.open.com.cn/api/core/file/gofile.do?id=PIlbmdxTEMP20160910105238781.png&amp;appkey=5da97a028134420c84123474e7e59e93" title="blob.png" alt="blob.png"></p>

B、<p><img src="http://oapi.open.com.cn/api/core/file/gofile.do?id=PItgjomTEMP20160910105249916.png&amp;appkey=5da97a028134420c84123474e7e59e93" title="blob.png" alt="blob.png"></p>

C、<p><img src="http://oapi.open.com.cn/api/core/file/gofile.do?id=PIxrmsyTEMP20160910105301832.png&amp;appkey=5da97a028134420c84123474e7e59e93" title="blob.png" alt="blob.png"></p>

D、<p><img src="http://oapi.open.com.cn/api/core/file/gofile.do?id=PIxwrltTEMP20160910105312821.png&amp;appkey=5da97a028134420c84123474e7e59e93" title="blob.png" alt="blob.png"></p>