The given words "itis", "inflammation", "pain", and "tumor" are all related to medical conditions. Out of these, "inflammation" is the correct answer as it is a general term used to describe the body's response to injury or infection, characterized by redness, swelling, heat, and pain. "itis" is a suffix commonly used in medical terminology to indicate inflammation of a specific organ or tissue. "Pain" is a symptom that can occur due to various reasons, including inflammation. "Tumor" refers to an abnormal growth of cells, which may or may not be associated with inflammation.