______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.
In a question, the subject and the verb must be inverted, which means the verb must come before the subject. Making it clearer, I will use this statement :
I think he is the richest man.
We are making question about him, so Who is he? I dont know. Now, I'll 1. take out the word him and add in the question word who in the beginning of the sentence. I will also 2. change the word I to you
Who you think is the richest man.
Now, I will 3. put the verb in front of the noun.The clause that should be inverted is "you think". Since the verb think is a normal verb which can't be inverted, the correct way to invert this sentence is adding the helping verb do right before "you think".
Who do you think is the richest man.
The correct answer is therefore, (A).