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．A scientific explanation of acoustics and the nature of sound.
B．A description of people's reactions to the newly renovated hall.
C．A discussion of the coffee shop that once was located in the building.
D．Further discussion about the activities of Isaac Stern in 1960.