The "Hygiene Hypothesis" Suggests That Asthma Is the Result of Minimal

The "hygiene hypothesis" suggests that asthma is the result of minimal childhood exposure to chemicals that cause asthma attacks.According to this hypothesis,exposure to allergens in childhood strengthens the immune system's response to these relatively harmless molecules,making asthma cases uncommon.
-The hygiene hypothesis predicts that the lowest levels of asthma should occur in people living in

A) poor rural families in developing countries.
B) wealthy families in developing countries.
C) poor urban families in developed countries.
D) wealthy families in developed countries.