Dr Menteur Runs a Study in Which Infertile Women Are

Dr. Menteur runs a study in which infertile women are given injections of a synthetic hormone in hopes it will cause them to ovulate. Unknown to the women, the injections also contain a chemical that is hypothesized to increase the chance that fertilized eggs will implant in their uteruses. None of the participants experience any negative side effects from this second chemical, and more of the women become pregnant than in previous studies using just the hormone. The women are not paid for participating in the study, although they receive the treatment for no cost. This study is:

A) ethical, because the second chemical did not harm the women.
B) ethical, because the second chemical increased the chance the participants would achieve their desired outcome.
C) unethical, because the women were not paid for their participation in the study.
D) unethical, because the women were not informed injections would contain the second chemical.