单选题 Which of the following indicates the acceptable range of variation of a process as represented on the control chart?
A) Mean. B) Specification limit.
C) Rule of seven. D) Upper and lower control limits.

【正确答案】 D

【答案解析】[解析] 下列哪项指出了在控制图中过程变量的可接受范围?
A) 平均值。 B) 规格限制。
C) 七点规则。 D) 控制上限和下限。