How many people know that the term "arthritis" may refer to dozens of different types of joint involvement ?

【正确答案】 A

【答案解析】解析：句意：有多少人了解“关节炎”这个词可能是指几十种不同类型的关节失调?involvement混乱；缠绕。disorder紊乱，失调。knuckle指节，关节。dislocation脱臼。therapy治疗，疗法。