Correct Answer: B,E
Explanation/Reference:
B: A snapshot standby database can be converted back into a physical standby database at any time.
E: You create a logical standby database by first creating a physical standby database and then transitioning it to a logical standby database.
Incorrect Answers:
A: Oracle Database supports the installation of database software upgrades, and the application of patch sets, in a rolling fashion-with near zero database downtime-by using Data Guard SQL Apply and logical standby databases.
C: A cascaded redo transport destination (also known as a terminal destination) receives primary database redo indirectly from a standby database rather than directly from a primary database. Only physical standby databases can cascade redo.
D: A snapshot standby cannot be the target of a switchover or fast-start failover operation.
References: https://docs.oracle.com/cd/E11882_01/server.112/e41134/create_ls.htm#SBYDB4732
https://docs.oracle.com/cd/E11882_01/server.112/e41134/manage_ps.htm#SBYDB00580