It Is Ethically Impossible to Conduct Experimental Studies of Stress

It is ethically impossible to conduct experimental studies of stress and immune responses in humans to determine whether severe stress and prolonged stress actually causes susceptibility to health problems.However, some researchers have measured ________ and found that ________.

A) immune responses; loud noises can suppress immune responses
B) reports of illness; people who experience stress are ill more often
C) immune responses; even minor stressors can suppress immune responses
D) bacterial infections; stressors can increase infection rates