The conclusion of this argument is: "it is generally unwise for patients to have medical checkups when they do not feel ill."
Why? A physician who is too thorough could subject a patient to discomfort and expense of unnecessary tests. A physician who is not thorough enough could miss a serious problem and give the patient a false sense of security. We are also told that it is difficult for physicians to judge exactly how thorough they should be.
We are looking for the answer choice that breaks apart the reasoning in the argument, either by showing that a premise given in support of the conclusion is false or that the conclusion does not necessarily follow.
Answer choice (A) states: "Some serious diseases in their early stages have symptoms that physicians can readily detect, although patients are not aware of any problem."
This would seriously weaken the argument because the conclusion would no longer follow. If there are some serious diseases that have symptoms in the early stages--which patients are not aware of, but can be readily detected by physicians--then it would not be generally unwise for patients to have medical checkups when they do not feel ill, since these serious diseases would not be detected otherwise.
Thus, answer choice (A) breaks down the reasoning in our argument, meaning it is our correct answer.
Hope that was helpful! Please let us know if you have any other questions.
