题目内容：
根据以下内容，回答题。The fitness movement that began in the late 1960s and early 1970s centered around aerobicexercise . Millions of individuals became engaged in a variety of aerobic activities, andliterally thousands of health spas developed around the country to capitalize ( 获利) on thisemerging interest in fitness, particularly aerobic dancing for females. A number of fitness spasexisted prior to this aerobic fitness movement, even a national chain with spas in most major cities.However, their focus was not on aerobics, but rather on weight-training programs designed todevelop muscular mass, strength, and endurance in their primarily male enthusiasts. These fitnessspas did not seem to benefit financially form the aerobic fitness movement to better health, sincemedical opinion suggested that weight-training programs offered few, if any, health benefits. Inrecent years, however, weight training has again become increasingly popular for males and forfemales. Many current programs focus not only on developing muscular strength and endurance buton aerobic fitness as well.
Historically, most physical-fitness tests have usually included measures of muscular strengthand endurance, not for health-related reasons, but primarily because such fitness componentshave been related to performance in athletics. However, in recent years, evidence has shown thattraining programs designed primarily to improve muscular strength and endurance might also offersome health benefits as well. The American College of Sports Medicine now recommends thatweight training be part of a total fitness program for healthy Americans. Increased participation in
such training is one of the specific physical activity and fitness objectives of Healthy People 2000:National Health Promotion and Disease Prevention Objectives.
The word "spas" (Line 3, Para.1 ) most probably refers to A．sports activities
B．places for physical exercise
C．recreation centers
D．athletic training programs
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