Sample observations of a claims processor made over a 160-hour work month reveal that the worker produced a total of 384 completed claims forms. The performance rating was 80%. The worker was idle 20% of the time. The allowance factor is 8%. What is the standard time per unit?
A) 0.42 minutes
B) 16.0 minutes
C) 17.4 minutes
D) 20.0 minutes
E) 21.7 minutes