Psychologist Sheldon Cohen and His Colleagues Conducted a Carefully Controlled

Psychologist Sheldon Cohen and his colleagues conducted a carefully controlled study examining the relationship between stress and susceptibility to the common cold. What were the results of this study?

A) Increased susceptibility to colds was not related to the volunteers' level of stress but rather to unhealthy behaviors, such as poor diet and smoking.
B) The only factor that caused increased susceptibility to colds among the volunteers in the study was exposure to the nasal spray containing the cold virus.
C) The level of stress that the volunteers reported was very strongly related to their susceptibility to the common cold virus.
D) The only factor that caused increased susceptibility to colds among the study's volunteers was sharing an apartment with another person who already had the cold virus.