After an extraordinarily stressful week at work, Mahmoud spends the weekend in bed with the flu. ...

After an extraordinarily stressful week at work, Mahmoud spends the weekend in bed with the flu. Which of the following best explains why Mahmoud became ill?
 
  a. Mahmoud depleted his body's stress-fighting resources, thus increasing his susceptibility to illness.
  b. Prolonged activity of Mahmoud's stress-fighting resources caused other bodily systems to break down,increasing his susceptibility to illness.
 c. Mahmoud's natural stress-fighting resources weakened with prolonged use, making his body more susceptibleto illness.
 d. Mahmoud has a Type B, rather than a Type A, personality.