A DevOps engineer has created the below AWS CloudWatch Event rule to capture the CloudFormation API call:

Answer options:

A.AWS API Call via CloudTrail cannot be used in a CloudWatch Event rule. 
B.CloudTrail can only trace the add and delete for a CloudFormation stack. No API call is recorded for the stack update, so no notification was received.
C.The rule should be changed as the following snippet:
{
"source": [
"aws.cloudtrail"
],
"detail": {
"eventSource": [
"cloudformation.amazonaws.com"
]
}
}
D.Check if CloudTrail logging is turned on in this region. If it is turned off, no AWS API action events can be received.

Correct Answer – D
When a CloudWatch Event rule is created, the event type can be selected as "AWS API Call via CloudTrail". For its details, check the documentation in
https://docs.aws.amazon.com/AmazonCloudWatch/latest/events/Create-CloudWatch-Events-CloudTrail-Rule.html.
Option A is incorrect: Because the CloudTrail API call is a valid event type in the CloudWatch Events rule.
Option B is incorrect: Because stack update is also captured and reflected in CloudTrail.
Option C is incorrect: The "detail-type" should be "AWS API Call via CloudTrail":
Option D is CORRECT: Because "AWS API Call via CloudTrail" in CloudWatch Events Rule relies on the functions provided by CloudTrail. So, CloudTrail should be turned on first; otherwise, the Events Rule cannot be triggered.