Options offered by Hugh Darrow and Eliza Cassan will always be available; however, you need to rescue (though not required to access the final stage) David Sarif and William Taggart to achieve their epilogues.
The endings each will have slightly different narration from Jensen as he reflects on his own actions, depending on whether you employed peaceful means (good), took violent action (evil), or a mix of both methods (neutral) whenever dealing with situations throughout the game. This means that the game has twelve unique endings.
Hugh Darrow: I Want To BelieveEdit
Requirements: Follow Darrow's request, in which nothing is held back and all information is revealed to the world. It is not explicitly stated whether all biotech research is banned, but Jensen remarks that humanity will surely fear it.
David Sarif: Terrorists Did It Edit
Requirements: Follow Sarif's request, where the blame will be laid at the feet of Humanity Front. This causes people to shift their anger towards extremism and allows research and technology to progress unfettered.
William Taggart: It Was Something In The WaterEdit
Requirements: Follow Taggart's request, this choice covers up the truth and places the blame on Neuropozyne poisoning. This results in stronger regulation, ultimately strengthening the Illuminati's position.
Self Destruction: The Truth Is Out ThereEdit
Requirements: Do not select any of the three above messages to send, but instead activate Panchaea's self-destruct mechanism. The rationale given for this action is that Jensen feels that it is not up to Darrow, Taggart, Sarif, nor even himself to determine mankind's fate. He has faith that humanity will eventually do what is best, and this is why he elects to remove them all from the equation.