Which two statements are correct about the default Oracle VDI built-in database configuration?

Which two statements are correct about the default Oracle VDI built-in database configuration?

A.
Thesecondary database is not active unlesstheprimary host is unavailable.

B.
Allnon-primary VDI Center hosts have a read-only copy of the database.

C.
The first secondary hostadded to the VDI Center runs a slave database.

D.
There is one primary host and two secondary hosts in a VDI Center always.

Explanation:
http://docs.oracle.com/cd/E26217_01/E35769/html/vdi-centers-about.html(see 2.1.2)