Physician: In order to investigate diseases caused by hormonal imbalances, a certain researcher wants to study, among others, 200 children whose pituitary glands fail to produce typical amounts of Human Growth Hormone (HGH). The study would involve administering a synthetic version of HGH to the children over a two-year period. But medical research should be permitted only if it is likely to reveal important information about a medical condition and is known to pose only a minimal risk to the subjects. The researcher' s proposed study should be prohibited. Which one of the following, if true, would most help to justify the physician's argumentation? ['About 10, 000 children have already been given synthetic HGH without obvious side effects.', 'Obtaining informed consent from children is impossible, because they are not yet mature enough to understand complex medical issues.', 'Although hormonal imbalances can cause disease, the imbalances themselves do not constitute a medical condition.', 'The long-term effects of synthetic HGH have never been tested and are unknown.']