Cortisol will rule ______ Addison's.

• A. In
• B. Out
• C. Within
• D. Beyond

Answer: (B)

Rule out means to exclude a diagnosis based on the test result. If cortisol is adequate (normal or high), Addison's disease (adrenal insufficiency) is unlikely, so cortisol will rule Addison's out. Addison's presents with low cortisol, so a normal/high level helps differentiate and avoid mislabeling the condition. The other prepositions don’t fit this diagnostic idea, so the correct choice is “Out.”