Stress can affect the respiratory system by __. A．decreasing the pulse rate B．a loss of carbon dioxide C．causing breathing problems D．causing asthma

A.decreasing
B.a
C.causing
D.causing

【参考答案】

C
第二段中提到，压力会影响到呼吸(respiratory)系统，会引起哮喘症(asthma)，使人呼吸加快。