Where do you control lightning knowledge settings and page layout?

Answer options:

A.Record Types
B.Article Types
C.Object Manager
D.Personal setting

Correct Answer: C 
Once knowledge in enabled, you can control its settings and page layout through going to set up, then access object manager. 
Option A is incorrect because record types are used whenever you have different processes. 
Option B is incorrect because article types provide the format and display how your article will show to the audience. 
Option C is incorrect. Through personal settings, you update your personal setting whether for changing your password or managing your chatter or customizing your tabs. 
Reference:

https://help.salesforce.com/articleView?id=knowledge_lightning_enable.htm&type=5