Answer:
I think that usually it means D, stating the truth, but honesty doesn't only mean telling the truth though. I think that the most logical option is B? I could be wrong though.
Explanation:
Because if you look up "ethical" on Dictionary.com it says: "pertaining to or dealing with morals or the principles of morality; pertaining to right and wrong in conduct." and if you look it up on Thesaurus.com the top two synonyms are honest and honorable. So I would says it is B, It is doing what is ethical. But I don't know for sure, I just think that that's the most reasonable.
Have a great days and I hope that this helps!!
