Q4:

Which of the following most logically completes the passage?

Appendicitis (inflammation of the appendix) is potentially fatal; consequently, patients with symptoms strongly suggesting appendicitis almost always have their appendix removed.  The appropriate surgery is low-risk but performed unnecessarily in about 20 percent of all cases.  A newly developed internal scan for appendicitis is highly accurate, producing two misdiagnoses for every 98 correct diagnoses.  Clearly, using this test, doctors can largely avoid unnecessary removals of the appendix without, however, performing any fewer necessary ones than before, since ______.

1. the patients who are correctly diagnosed with this test as not having appendicitis invariably have medical conditions that are much less serious than appendicitis
2. the misdiagnoses produced by this test are always instances of attributing appendicitis to someone who does not, in fact, have it
3. all of the patients who are diagnosed with this test as having appendicitis do, in fact, have appendicitis
4. every patient who is diagnosed with this test as having appendicitis has more than one of the symptoms generally associated with appendicitis
5. the only patients who are misdiagnosed using this test are patients who lack one or more of the symptoms that are generally associated with appendicitis

正确答案是B. 不是很明白。C为什么不对呢？ 请高手赐教。谢谢