In this case we have run the impdp without performing any conversion if endian format is different then we have to first perform conversion.

B (not C): You can validate that all database files and archived redo logs can be backed up by running a command as follows:
RMAN> BACKUP VALIDATEDATABASE ARCHIVELOG ALL;
This form of the command would check for physical corruption. To check for logical corruption,
RMAN> BACKUP VALIDATE CHECK LOGICAL DATABASE ARCHIVELOG ALL;
D: You can use the VALIDATE keyword of the BACKUP command to do the following:
Check datafiles for physical and logical corruption
Confirm that all database files exist and are in the correct locations.
Note:
You can use the VALIDATE option of the BACKUP command to verify that database files exist and are in the correct locations (D), and have no physical or logical corruptions that would prevent RMAN from creating backups of them. When performing a
BACKUP...VALIDATE, RMAN reads the files to be backed up in their entirety, as it would during a real backup. It does not, however, actually produce any backup sets or image copies (Not A, not E).

Explanation/Reference:
Explanation:
Keyword: shows the difference.
* Full ADDM analysis across two AWR snapshot periods
Detects causes, measure effects, then correlates them
Causes: workload changes, configuration changes
Effects: regressed SQL, reach resource limits (CPU, I/O, memory, interconnect) Makes actionable recommendations along with quantified impact
* Identify what changed
/Configuration changes, workload changes
* Performance degradation of the database occurs when your database was performing optimally in the past, such as 6 months ago, but has gradually degraded to a point where it becomes noticeable to the users. The Automatic Workload Repository (AWR) Compare Periods report enables you to compare database performance between two periods of time.
While an AWR report shows AWR data between two snapshots (or two points in time), the AWR Compare Periods report shows the difference (ABE) between two periods (or two AWR reports with a total of four snapshots). Using the AWR Compare Periods report helps you to identify detailed performance attributes and configuration settings that differ between two time periods.

* SQL Access Advisor is primarily responsible for making schema modification recommendations, such as adding or dropping indexes and materialized views. SQL Tuning Advisor makes other types of recommendations, such as creating SQL profiles and restructuring SQL statements.
* The query optimizer can also help you tune SQL statements. By using SQL Tuning Advisor and SQL Access Advisor, you can invoke the query optimizer in advisory mode to examine a SQL statement or set of statements and determine how to improve their efficiency. SQL Tuning Advisor and SQL Access Advisor can make various recommendations, such as creating SQL profiles, restructuring SQL statements, creating additional indexes or materialized views, and refreshing optimizer statistics.
Note:
* Decision support system (DSS) workload
* The library cache is a shared pool memory structure that stores executable SQL and PL/SQL code. This cache contains the shared SQL and PL/SQL areas and control structures such as locks and library cache handles.
References: