You need a CloudWatch alarm that stops EC2 instances when the average NetworkPacketsIn is less than 5 for at least 3 hours within a 12-hour window, evaluating hourly, and instances must continue running if metric data is missing during the evaluation. The alarm uses a threshold of 5 and a 1-hour evaluation period. What additional settings are required?

The correct answer specifies "Datapoints to Alarm to 3 out of 12" because the alarm needs to trigger if the condition is met for 3 hours within a 12-hour window, evaluating hourly. This means 3 consecutive or non-consecutive data points over 12 periods. "Treat missing data as not breaching the threshold" is crucial because the instances must continue running if metric data is missing, preventing false alarms. Finally, "add an EC2 action to stop the instance" is the correct action type for stopping an EC2 instance directly from a CloudWatch alarm. Incorrect options: "Treat missing data as breaching the threshold" would stop instances unnecessarily when data is missing. "Datapoints to Alarm to 9 out of 12" would require 9 hours of low activity, not the specified 3 hours. "Systems Manager action to stop the instance" is not the direct, built-in action for stopping an EC2 instance from a CloudWatch alarm; EC2 actions are used for this purpose.