Jim Went to His Doctor After Feeling Very Tired for a Few

Jim went to his doctor after feeling very tired for a few days. The doctor told Jim he had either a bacterial infection or mononucleosis. He administered a mononucleosis test, but Jim tested negative. The doctor then wrote Jim a prescription for antibiotics.
Which one of the following most accurately describes the method of reasoning used by Jim's doctor?

A) An observation about one symptom is used to make a determination about a similar symptom.
B) A generalization is reached by understanding a specific case.
C) A conclusion is reached by ruling out all other possible explanations.
D) A test is used to determine which of many possibilities is correct.
E) A generalization is rejected because it failed to apply to a specific case.