What is a possible medication included in DMARD therapy for rheumatoid arthritis?

In the context of managing rheumatoid arthritis, disease-modifying antirheumatic drugs (DMARDs) are critical as they aim to slow disease progression and prevent joint damage. Azathioprine, which is included in the correct answer, is one such DMARD used in the treatment of rheumatoid arthritis. It works by suppressing the immune system to reduce inflammation and halt the autoimmune process that leads to joint destruction.

The other medications listed serve different purposes. Ibuprofen, a non-steroidal anti-inflammatory drug (NSAID), is utilized primarily for its pain-relief and anti-inflammatory effects but does not alter the disease course. Prednisone is a corticosteroid often used for short-term control of flare-ups due to its significant anti-inflammatory properties, but it is not classified as a DMARD because it does not address the underlying autoimmune process long term. Acetaminophen is primarily an analgesic and antipyretic, providing pain relief but lacking anti-inflammatory effects and capability to modify disease activity.

Thus, Azathioprine stands out as the appropriate choice within the scope of DMARD therapy, uniquely characterized by its role in modifying the disease course in rheumatoid arthritis.