【单选题】

Which of the following statements is true with regard to the Houston Airport experiment
A．Professor Richard Larson hates queuing so much that he tears his hair out.

B．According to Larson' s study, the long waiting was the cause of annoyance.
C．When all the travelers had to wait for 2 minutes, there were a lot of complaints.
D．When the walking time was extended to 6 minutes, there were hardly any complaints.