Between 1997 and 2002, the incidence of peanut allergies in young children doubled, according to studies by medical allergists. The sharp rise in peanut and other food allergies in adolescents led scientists and doctors to look for possible causes and contributing factors. One idea gaining support is the "hygiene hypothesis," which suggests that the human immune system requires contact with a wide range of environmental pathogens in order to strengthen itself. In a home environment that is kept largely sterile, particularly through the use of antibacterial soaps and sprays, the body does not learn to recognize and later combat some harmful viruses and bacteria. The absence of germs to fight, some theorize, leads the immune system to begin focusing on other, more innocuous substances such as peanuts, milk, and eggs. As a result of the overly clean environment, the developing autoimmune reaction becomes too sensitive to other organisms. Unfortunately, even if there is sufficient evidence to support the hygiene hypothesis, the benefits of that knowledge are mixed. Few people would want to resort to introducing germs, avoiding vaccines, or purposely living less sanitary lives in hopes of preventing a mere possibility of food allergies.

In the passage, what purpose do the highlighted sentences serve?

(A) The first sentence states the main idea of the paragraph, and the second sentence states the secondary idea.
(B) The first sentence states a counterargument to the author's argument, and the second sentence provides a supporting detail.
(C)The first sentence identifies a problem, and the second sentence argues a solution.
(D) The first sentence introduces the main idea of the paragraph, and the second sentence is a supporting statement for the conclusion.
(E) The first sentence is the primary argument, and the second sentence is a secondary argument.