I think the period mark is a typo, the sentence only makes sense without it. 这房子里究竟哪一样。是你挑选的呢 (X) 这房子里究竟哪一样(東西)是你挑选的呢 (O) - What (thing) in the house was actually chosen by you? The punchline is '我太太' (my wife) -- The only thing in the house that was chosen by him was his wife


老王回答:“所有的家具都是我太太挑选的。” 我终于忍不住问道:“这房子里究竟哪一样,是你挑选的呢?” 老王思考了片刻,说:“我太太。” My translation goes like this Lao Wang replied: "All the furniture was my wife's decision." I finally couldn't help asking, "Is there anything in the house that was your decision?" Lao Wang thought for a moment and said, "My wife."

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