Which two tasks must you perform before you begin the upgrade process to Oracle Database 12c? (Choose two.)
A. Put all readonly tablespaces in read write mode
B. Recompile all invalid objects
C. Set the compatible parameter to 12.1.0.1
D. Gather dictionary statistics
E. Empty all user recycle bins
https://docs.oracle.com/en/database/oracle/oracle-database/12.2/upgrd/database-preparation-tasks-to-complete-before-upgrades.html#GUID-58C1A4B9-32F4-44E5-B82B-5D0EC78A6AE2
A -> no because there is an option “-T” for offline/read-only tablespace
B -> maybe, Oracle strongly recommends
C -> no, Oracle strongly recommends that you update both your earlier release and your new release Oracle Database to the latest BP or PSU but doesn’t mention compatible parameter
D -> maybe, Oracle strongly recommends
E -> yes it’s mandatory for avoiding errors