Which two pieces of tuningrelated information can you examine in the alert log to identify possible causes?

As a DBA, you notice a change in the performance of your database. Which two pieces of tuningrelated information can you examine in the alert log to identify possible causes? (Choose two.)

A.
the number of block corruption errors

B.
SQL statements that are consuming maximum resources

C.
the top five sessions that are consuming maximum resources

D.
the instance parameter values that have been changed using ALTER SYSTEM since the last
baseline