[单项选择] Under existing law, a new drug may be labeled, promoted, and advertised only for those conditions in which safety and effectiveness have been demonstrated and which the Food and Drug Administration (FDA) has approved, or so-called approved uses. Other uses have come to be called "unapproved uses", and cannot be legally promoted. In a real sense, the term "unapproved" is a misnomer because it includes one phrase two categories of marketed drugs that are very different. It is common for new research and new insights to identify valid new uses for drugs already on the market. Before such advances can result in new indications for inclusion in drug labeling, however, the available data must meet the legal standard of substantial evidence derived from adequate and well-controlled clinical trials. Such evidence may require time to develop, and, without initiative on the part of the drug firm, it may not occur at all for certain uses. However, because medical literature on new uses exi
A. tile increased cost to the patient of buying an FDA approved drug
B. the availability of publications to inform physicians of the existence of such uses
C. the time lag between initial discovery of a medical use and FDA approval of that use
D. the possibility that a medically beneficial use may never be clinically documented