If customers are returning shirts because of crooked collars, the people most likely to identify the cause of the problem are______.

A．to inform us that people are dissatisfied with their wages and hours.
B．to explain that "job enrichment" creates job.
C．to suggest that bosses hinder production more than they help it.
D．to persuade us to carry out our greater" job simplification".

A．several months.
B．about a year.
C．half a year.
D．several years.