Physicians noticed that women in their care undergoing hormone replacement therapy, a treatment for addressing extreme changes in hormone levels, tended to experience heart disease significantly less often than women not undergoing the therapy. However, when formal studies were then undertaken to confirm that hormone replacement therapy prevents heart disease, the results were mixed and indicated that in some cases hormone replacement therapy may cause heart disease.
Which of the following, if true, would best explain why the results of the formal studies differed from what physicians had observed?
A. The original reason for using hormone replacement therapy was not to prevent heart disease but rather to mitigate discomfort caused by changes in levels of hormones.
B. Many physicians who have worked with women using hormone replacement therapy have not specialized in the treatment of heart disease.
C. The women who underwent hormone replacement therapy before the studies mentioned were done tended to be more educated women who were careful about taking care of their health.
D. Some women participating in the formal studies of hormone replacement therapy and heart disease continued to smoke while undergoing the therapy.
E. The links between hormone replacement therapy and heart disease have become better understood with years of study.
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