Which two statements are true regarding the Automatic Diagnostic Repository (ADR) in Oracle Database 11g?

Which two statements are true regarding the Automatic Diagnostic Repository (ADR) in Oracle
Database 11g? (Choose two.)

A.
A single ADR can support multiple ADR homes for different database instances.

B.
The alert files are stored in XML file format in the TRACE directory of each ADR home.

C.
If the environmental variable ORACLE_BASE is set, then DIAGNOSTIC_DEST is set to
$ORACLE_BASE.

D.
The BACKGROUND_DUMP_DEST initialization parameter overrides the DIAGNOSTIC_DEST
initialization parameter for the location of the alert log file.