Multi-select problem: How does the next paragraph end?

How to activate 2 step verification in facebook
Install the facebook app on on your mobile phone.
Facebook uses a code generator tool in the facebook app as a two-factor security system. You'll be prompted to open the facebook app and enter the code from the code generator.

OPTIONS:
a). You'll be instructed by a screen that asks for your password. Input your password as one of the field boxes.
b). If you have any questions or are unsure about a time period in which you'd like to activate this code, launch two step authentication using facebook. Tap the app store from your phone.
c). Facebook users will be required to provide a valid username, password, and password as well as a twitter or instagram id. Information regarding the code generator tool may be asked for via the app's user interface to determine if you've added properly-known usernames and passwords.
d). This only happens when you log into facebook on an unknown computer. If you can't use the facebook app or code generator, facebook will send your phone a text message with the code.
d).