To automate the instantiation of a PDB in the standby database after creating a remote clone in the primary database, certain conditions must be met:
Open PDBI (remote clone source) in Read Only (A): The source PDB from which the clone is created must be open in read-only mode to ensure a consistent state during cloning.
Set STANDBY_PDB_SOURCE_FILE_DIRECTORY to <location of the PDB> in the london database (C): This parameter specifies the location on the standby database where the files from the source PDB should be placed.
Set STANDBY_FILE_MANAGEMENT to auto in the london database (F): This parameter automates the management of file changes on the standby database when structural changes occur on the primary database, ensuring that the clone operation is reflected automatically on the standby.
Reference:
Oracle Multitenant Administrator's Guide
Oracle Data Guard Broker documentation

The execution of the UNSKIP procedure is designed to remove SQL Apply filters that have been previously set up on a logical standby database. Based on the provided statements, the UNSKIP procedure is directed to delete any SQL Apply filters for DML statements associated with objects in the 'HR' schema that start with
'EMP'. Since both SKIP procedures had the same schema name ('HR') and statement type ('DML'), and the UNSKIP procedure uses a wildcard (%) for the object name, it will successfully remove both of the SQL Apply filters for 'EMP_NEW' and 'EMP_OLD', as both object names match the pattern provided in the UNSKIP procedure.
References:Oracle's Data Guard documentation and SQL Language Reference provide insights into managing SQL Apply filters on a logical standby database using the DBMS_LOGSTDBY package. This includes adding and removing filters through SKIP and UNSKIP procedures.

Real-Time Query is a feature that allows queries to be run on a physical standby database while it is applying redo data. The relevant truths about it are:
* Setting standby_max_data_delay=0 requires synchronous redo transport (A): For the real-time apply feature to function with no data delay (zero delay), synchronous redo transport must be used. This setting ensures that the data on the standby database is as current as possible before queries are executed against it.
* Disabling Real-Time Query prevents the automatic start of redo apply when a physical standby database is opened read-only (C): If Real-Time Query is disabled, opening the standby database in read-only mode will not start the redo apply process automatically. Redo apply needs to be manually started to synchronize the standby database with the primary.References:
* Oracle Data Guard Concepts and Administration Guide

Automatic Block Media Recovery can be a significant feature for maintaining data integrity within a Data Guard configuration.
A corrupt block on the primary database can be automatically recovered, using a block from a standby database with Real-Time Query enabled (A): When a corrupted block is encountered on the primary database, Oracle can automatically replace it with a good block from the standby database where Real-Time Query is enabled, leveraging the standby as a source of good data.
A corrupt block on the primary database is automatically recovered, using a block from a flashback log from the primary database (E): If a good block version is available in the flashback logs of the primary database, Automatic Block Media Recovery can use it to recover the corrupted block on the primary.
Reference:
Oracle Database Backup and Recovery User's Guide