C is the only correct answer. Many people think "bona fide" is "bonafide" or "bona fied" or some variation of that, but it's a Latin phrase meaning "in good faith" and generally means you're talking about the real McCoy.

The others:

• A features the common error in which "lead" is used as the past tense of "lead" in the same way "read" is the past tense of "read." Sorry, but if you pronounce "lead" to rhyme with "red," you're talking about the metal. The past tense of "lead" is "led."
• B features the common error of using "adieu" instead of "ado." "Adieu" is a French word meaning goodbye, so I don't know how people end up misusing it (without further goodbye?), but "ado" means fuss and trouble. Remember the Shakespeare play Much Ado About Nothing? Yup.
• D features the common error in which "piece" is substituted for "peace." To "hold your peace" is to be quiet. To "hold your piece" is either a reference to holding an actual piece of something (a puzzle? a handgun?) or perhaps an obscene suggestion. Problem is, people think of the instance in which you can "SAY your piece," and that's probably where the confusion comes from.