Question：What is the learning curve theory?
　　A. The cumulative average time per unit produced is assumed to increase by a constant percentage every time total output of the product doubles.
　　B. The cumulative average time per unit produced is assumed to double every time total output of the product doubles.
　　C. The cumulative average time per unit produced is assumed to decrease by a constant percentage every time total output of the product doubles.
　　D. The average time per unit produced is assumed to decrease by a constant percentage every time total output of the product changes by that constant percentage.
　　The correct answer is: The cumulative average time per unit produced is assumed to decrease by a constant percentage every time total output of the product doubles.
　　For instance, when an 80% learning effect occurs, the cumulative average time required per unit of output is reduced to 80% of the previous cumulative average time when output is doubled.