This is not compatible with the experiment’s results. If gamma interferon does what (A) claims, it would interfere with the mechanism that makes MS so destructive. This would likely improve MS patients’ conditions—this contradicts the experiment, which shows the opposite effect.

This could be true and may explain why gamma interferon makes MS patients’ conditions worse. By causing an increase in white blood cells, gamma interferon could increase the number of cells attacking the myelin sheath in MS patients.

This could be true and may explain why gamma interferon makes MS patients’ conditions worse. It suggests an association between increased gamma interferon levels and MS attacks.

This could be true. It suggests that scientists’ initial belief that MS is triggered by viral infections is incorrect. This could explain why gamma interferon, one of the body’s antiviral tools, is ineffective against it.

This could be true and may explain why gamma interferon makes MS patients’ conditions worse. It suggests that inhibiting gamma interferon levels improves patients’ conditions—this is consistent with the finding that increasing gamma interferon levels worsens patients’ conditions.