Restaurant manager: In response to requests from our patrons for vegetarian main dishes, we recently introduced three: an eggplant and zucchini casserole with tomatoes, brown rice with mushrooms, and potatoes baked with cheese. The first two are frequently ordered, but no one orders the potato dish, although it costs less than the other two. Clearly, then, our patrons prefer not to eat potatoes. Which one of the following is an error of reasoning in the restaurant manager's argument? ['ignoring possible differences between what people say they want and what they actually choose', 'treating one of several plausible explanations of a phenomenon as the only possible explanation', 'concluding that two things that occur at the same time have a common cause', 'drawing a conclusion that is inconsistent with one premise of the argument']