A MySQL replication slave is set up as follows:
Uses all InnoDB tables

Receives ROW-based binary logs

Has the read-only option

The replication slave has been found in an error state.
You check the MySQL error log file and find these entries:

What are two possible causes for this error to occur? (Choose two.)

You have just created a replication slave from a backup of the master made with mysqldump:

You try to log in to the slave with the application user, but fail as follows:

The login works on the master.
Which two changes to the process can fix the issue?

An admin attempts to enforce stronger security by using these commands:

The admin then leaves the system running with the specified changes. What are two remaining security concerns? (Choose two.)

An existing master-slave setup is currently using a delayed replication of one hour. The master has crashed and the slave must be "rolled forward" to provide all the latest data.
The SHOW SLAVE STATUSindicates these values:
* RELAY_LOG_FILE=hostname-relay-bin.00004
* RELAY_LOG_POS=1383
Which command set would make the slave current?
STOP SLAVE; SET GLOBAL master_delay=0; START SLAVE;

You are investigating the performance of the server and see this information:
* events_waits_summary_global_by_event_name in the Performance Schema shows that the wait/synch/mutex/sql/LOCK_table_cache event is dominating other wait events.
* The Table_open_cache_overflows status variable is 0.
Which action should be taken to remove the performance bottleneck described here?