You notice performance degradation in your production Oracle 12c database. You want to know what caused this performance difference. Which method or feature should you use? 

Answer options:

A. Database Replay
B. Automatic Database Diagnostic Monitor (ADDM) Compare Period report
C. Active Session History (ASH) report
D. SQL Performance Analyzer

B

Reference: http://docs.oracle.com/cd/E24628_01/server.121/e17635/tdppt_degrade.htm