Passage Summary: MS happens when the body's own defense cells attack the brain and spine. Doctors tried to treat it with a natural antiviral drug, thinking a virus was the cause, but it actually made the patients much sicker.

Reasoning: Multiple sclerosis involves the immune system attacking the body, and an antiviral treatment called gamma interferon unexpectedly made patients significantly worse in a 1984 study.

Analysis: For a 'Must be False' question, we need to find an answer choice that is directly contradicted by the facts provided. The stimulus tells us that gamma interferon—an immune system weapon—caused MS patients to get 'dramatically worse.' This suggests that boosting the immune response in an autoimmune disease is counterproductive. Look for an answer choice that claims gamma interferon is helpful for MS or that the immune system's activity is irrelevant to the disease's progression.