What Was the Result in the Case in the Text

What was the result in the case in the text, United States v. Sonya Evette Singleton, in which it was claimed that plea deals in which one defendant receives leniency in exchange for truthful testimony against another defendant are really bribes in violation of federal bribery law?

A) That such deals are illegal only if felony, as opposed to misdemeanor, offenses are involved.
B) That such deals are illegal only when white-collar offenses are involved.
C) That such deals are illegal.
D) That such deals are legal so long as the defendant receiving the plea deal is not completely exonerated.
E) That such deals are legal.