Facebook’s evolving privacy settings are a result of multiple revelations that user info was sold to third parties for research and advertising and new legislation aimed at protecting the privacy of social media users.
While the first option regarding self-monitoring could be seen as a contributing factor, the primary motivations have been public backlash related to privacy breaches and regulatory changes in response to those issues. However, if you need to select just one option from the choices provided, the most relevant answer would be the multiple revelations about user info being sold to third parties.