While stress and its effects on illness are generally thought of as negative or undesirable things, there is a benefit to those who suffer from increased stress being extra aware of the symptoms in their bodies. What is it?

a. They tend to see their doctor faster when they experience stress, so if they do have a serious illness early detection and early treatment are more likely.
b. Stress creates an increase in natural killer T cells and basophils, which are effective at fighting off some strains of serious illness, including malaria, Lyme disease, and multiple sclerosis.
c. People who experience this much stress often avoid seeing their doctors because they do not want to find out that they have a problem. This frees up the doctor to spend her or his time seeing patients with real problems.
d. Stress helps to keep people "on edge," which is when the heart functions most effectively.

Answer: A