How Can Someone Maintain Credibility and Goodwill While Acknowledging a Mistake

How can someone maintain credibility and goodwill while acknowledging a mistake has been made?

A) Minimize the potential damage from the mistake.
B) Provide a long list of reasons why the mistake was made.
C) Identify all those who were instrumental in supporting the bad decision.
D) Take responsibility for the mistake.
E) Send a letter of apology to all affected by the mistake.