When you resize the Amazon RDS DB instance, Amazon RDS will perform the upgrade during
the next maintenance window. If you want the upgrade to be performed now, rather than waiting
for the maintenance window, specify the _____ option.

A.
ApplyNow

B.
ApplySoon

C.
ApplyThis

D.
ApplyImmediately

Explanation:
http://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Overview.DBInstance.Modifying.html