What is the best answer for the question "How would you deal with a difficult customer?" in an interview for a customer service job position?

As far as i understtod from the question is that you mean by difficult customers are the customers who are very demanding, and those kind of customers can be dealt with by being assertive, short answered and specific in to the customer request, otherwise the customer will be opening many side conversations and questions that will be hard to control the conversation after that. need to mentione that you have to be very calm and careful in chosing your words.

e hard customer tends to create a kind of confusion in the seller's words and if the seller can convince the customer that there is a substantial difference, he can sell his product

I would say,

I will be listening very carefully and won't say a word back while he/she is talking. My response at the end will be I will be happy to take care of your issue and will apologize for the inconvience. I will keep my divine smile and letting the customer feel that he/she is in good hands.