Answer: C

The font used for the trade name of the drug shall not be larger than one-half of the font used for the generic name in terms of single character area, so A is wrong; the use of unused fonts in drug instructions and labels is prohibited. Registered trademarks and other drug names that have not been approved by the State Food and Drug Administration, so B is wrong; generic drug names must not use cursive script, seal script and other difficult-to-recognize fonts, so D is wrong; drug trade names should comply with the "Drug Trade Names" "Nomenclature Principles" and can only be used after approval by the Drug Supervision and Administration Department of the State Council, so E is wrong.