Which product should your customer use?

Your customer needs server availability that provides uninterrupted access to database services,
handling any unexpected failure of one or more machines hosting the database server, due to a
hardware or software fault. Which product should your customer use?

A.
Oracle Data Guard

B.
Oracle Streams

C.
Oracle Real Application Clusters

D.
Oracle GoldenGate

Explanation:
http://www.oracle.com/technetwork/database/availability/maximum-availability-wp-12c-1896116.pdf (page 5, Server HA: Oracle Real Application Clusters)