Step 1: Suppressive anti-inflammatory therapy in rheumatic fever is chosen according to whether the heart is involved, because carditis is the manifestation that carries long-term morbidity.
Step 2: When a patient has carditis, especially carditis with congestive heart failure, corticosteroids are the preferred agents. They suppress the inflammation more effectively than salicylates in significant cardiac involvement.
Step 3: In carditis without heart failure either steroids or aspirin may be used, with steroids generally preferred, while in patients without carditis aspirin alone is adequate. Total suppressive therapy lasts about 12 weeks.
Step 4: Chorea and subcutaneous nodules by themselves are not indications for steroid therapy, so options b, c and the all-inclusive option d are incorrect, leaving carditis as the answer.