Which statement below best describes what thresholds you can set to trigger a CloudWatch Alarm?

After setting up some EC2 instances you now need to set up a monitoring solution to keep track of these instances and to send you an email when the CPU hits a certain threshold.

Which statement below best describes what thresholds you can set to trigger a CloudWatch Alarm?
A . Set a target value and choose whether the alarm will trigger when the value is greater than (>), greater than or equal to (>=), less than (<), or less than or equal to (<=) that value.
B . Thresholds need to be set in IAM not CloudWatch
C . Only default thresholds can be set you can’t choose your own thresholds.
D . Set a target value and choose whether the alarm will trigger when the value hits this threshold

Answer: A

Explanation:

Amazon CloudWatch is a monitoring service for AWS cloud resources and the applications you run on AWS. You can use Amazon CloudWatch to collect and track metrics, collect and monitor log files, and set alarms.

When you create an alarm, you first choose the Amazon CloudWatch metric you want it to monitor. Next, you choose the evaluation period (e.g., five minutes or one hour) and a statistical value to measure (e.g., Average or Maximum).

To set a threshold, set a target value and choose whether the alarm will trigger when the value is greater than (>), greater than or equal to (>=), less than (<), or less than or equal to (<=) that value.

Reference: http://aws.amazon.com/cloudwatch/faqs/