AnaCarolina and Jaco, Executive Managers at Duke Manufacturing, Are Tasked

AnaCarolina and Jaco, executive managers at Duke Manufacturing, are tasked with determining appropriate performance metrics for the customer perspective of Duke's balanced scorecard. Which of the following is the best metric for this situation?

A) return on investment
B) operating throughout
C) material price variance
D) number of returns due to incorrect products shipped in response to orders