* Single sign-on (SSO): This allows users to sign in to their Chrome OS device using their organizational credentials. This is particularly useful in enterprise or educational settings where users already have an existing account.
* Facebook Connect: This allows users to sign in to their Chrome OS device using their Facebook credentials. This can be convenient for users who are already logged into Facebook on another device.
Options A and C are incorrect:
* SMS code sent to mobile phone: This is not a standard sign-in method for Chrome OS devices.
* Google Friend Connect: This was a social networking service that has been discontinued.