题目内容：
"Even exercise professionals concede half a point here" (Line 3, Para．2)means"They ( ) "． A．agree that the calories in a small piece of pastry can be difficult to work off by exercise
B．partially believe diet plays a supporting role in weight reduction
C．are not fully convinced that dieting can help maintain one's new weight
D．are not sufficiently informed of the positive role of exercise in losing weight
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答案解析：