Question：Which of the following correctly describes a standard hour?
　　A. An hour during which only standard units are made.
　　B. An hour during which no machine breakdowns occur.
　　C. The quantity of work achievable at standard performance in an hour.
　　D. An hour for which standard labour rates were paid.
　　The correct answer is: The quantity of work achievable at standard performance in an hour.
　　For example, if the standard time allowance per unit is 4 hours and 22 units are produced, output expressed in terms of standard hours will be 88 standard hours.