Who you think vs. who do you think?? - 英檢

這是某年的TOEFL考題，書很舊了答案給B. 很懷疑書是不是錯了!!
原因之一是很常有出現"who do you think you are?", 這豈不是和答案A很像嗎?
但又聽說上面的這個句子其實被口語化了所以不合乎文法了!

請問答案應該是哪一個呢?
--- ______in this town?
--- I think Mr. Kim is the richest man.　
　A Who do you think is the richest man
　B. Who you think is the richest man
(兩個選項就差一個"DO", 其他選擇明顯不對刪除了!)

很苦惱，謝謝!


另外，如果我寫成"who do you think the richest man is?"這樣對嗎?

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