What is the charge for the data transfer incurred in replicating data between your primary and
standby?

A.
No charge. It is free.

B.
Double the standard data transfer charge

C.
Same as the standard data transfer charge

D.
Half of the standard data transfer charge

Explanation:
Q: How much do Read Replicas cost? When does billing begin and end?
A Read Replica is billed as a standard DB Instance and at the same rates. Click here for
more information on DB Instance billing visit this FAQ. Just like a standard DB Instance, the
rate per “DB Instance hour” for a Read Replica is determined by the DB Instance class of the
Read Replica – please see Amazon RDS detail page for up-to-date pricing. You are not
charged for the data transfer incurred in replicating data between your source DB Instance
and Read Replica.
Billing for a Read Replica begins as soon as the Read Replica has been successfully created
(i.e. when status is listed as “active”). The Read Replica will continue being billed at standard
Amazon RDS DB Instance hour rates until you issue a command to delete it.