Which statement best characterizes the relationship between stress and illness?

Which statement best characterizes the relationship between stress and illness?
 
  a. Stress increases the number of lymphocytes in the bloodstream, which diminishes the body's ability to fight offdisease.
 b. Stress increases levels of adrenaline and other hormones that suppress immune cell activity and increasesusceptibility to illness.
 c. Stress increases the negative attributions that people make, and negative attributions can become self-fulfillingprophecies.
 d. Under high levels of stress, people tend to sleep too much, which weakens the immune system and makesillness more likely.