"There is NOTHING MORE DISTRESSING to every good patriot, to every good American, than the hard, scoffing spirit which treats the ALLEGATION of dishonesty in a public man as a cause for laughter. " - really good line imo
My best guess would be answer C.
My reasoning is the words used and the meaning behind them, without the need of being emboldened " nothing more distressing " is a powerful a way you can distinguish something to be distressing. The speaker/author is speaking powerfully; anent? I believe the speaker is having issues with how indifferent the public is reacting when a person of government has been dishonest (or when a person of government is accused of being dishonest). He says in fact that the "scoffing spirit" among people that take these allegations lightly, is to him, the most distressing event.
Therefore my best guess would be that this speaker is speaking with criticism towards those willing to hear.