If you have File Vault 2 enabled on your Mac, how do you start up from OS X Recovery?

A.
Hold the Command and R keys at startup.

B.
You must turn off disk encryption to use this feature.

C.
Use the Option key and choose OS X Recovery disk in the Startup Manager,

D.
Open System Preferences > Startup Disk preference pane, then select the OS X Recovery disk.

Explanation:

https://support.apple.com/en-us/HT202280