How can the user configure this?

A user is configuring a CloudWatch alarm on RDS to receive a notification when the CPU utilization of RDS is
higher than 50%. The user has setup an alarm when there is some inactivity on RDS, such as RDS unavailability.
How can the user configure this?

A.
Setup the notification when the CPU is more than 75% on RDS

B.
Setup the notification when the state is Insufficient Data

C.
Setup the notification when the CPU utilization is less than 10%

D.
It is not possible to setup the alarm on RDS

Explanation:
Amazon CloudWatch alarms watch a single metric over a time period that the user specifies and performs one
or more actions based on the value of the metric relative to a given threshold over a number of time periods.
The alarm has three states: Alarm, OK and Insufficient data. The Alarm will change to Insufficient Data when
any of the three situations arise: when the alarm has just started, when the metric is not available or when
enough data is not available for the metric to determine the alarm state. If the user wants to find that RDS is
not available, he can setup to receive the notification when the state is in Insufficient data.