Which of the Following Events Would Be the Strongest Evidence

Multiple Choice

Which of the following events would be the strongest evidence that a firm's efforts to improve quality control were achieving their desired result?

A) A survey of customers indicates a significant increase in the level of customer satisfaction.
B) The quality control department indicates that the number of defective parts has dropped significantly.
C) Costs per unit of output decline by more than 10 percent.
D) Total output increases by 20 percent without an increase in labour or materials.