Which of the following statements best describes the usual course of rheumatoid arthritis? (a) It is an acute exacerbation of joint pain treated with short-term anti-inflammatory therapy (b) It is a chronic disease characterized by acute changes within nonsynovial joints (c) It is an acute disease that is characterized by rapid synovial changes due to inflammation (d) It is a chronic disease characterized by acuteexacerbations followed by remissions with consequences associated with chronic inflammatory changes (e) It is a joint disease characterized by a marked loss of calcium from the bones and a resultant thinning of the bones