A photo-sharing application uses Amazon Aurora MySQL to store user data. A development team would like to enhance the application by sending a welcome email every time a new user is created. They’ve implemented an AWS Lambda function that will generate email text and send it using AWS SES. What is the optimal solution for triggering the Lambda function when a new user is created?

Answer options:

A.Update the application code to invoke the AWS Lambda function when it inserts a new user in the Amazon Aurora database.
B.Create a trigger and stored procedure in the Amazon Aurora database. In the stored procedure, call mysql.lambda_async function to trigger the AWS Lambda function.
C.Configure Audit Log export on the Amazon Aurora database. Configure CloudWatch subscription filter to trigger the AWS Lambda function.
D.Configure Audit Log export on the Amazon Aurora database. Configure CloudTrail SNS notification. Create an AWS Lambda subscription to the SNS topic.

Answer: B
Option A is incorrect because this option requires application code change. This is not an optimal solution.
Option B is CORRECT because Amazon Aurora MySQL mysql.lambda async function can be used within a stored procedure to invoke an AWS Lambda function. The stored procedure can be triggered when a new user is created.
Option C is incorrect because it is not the easiest and most cost-efficient solution. It consists of additional complexity involved with the configuration of Audit Log export and CloudWatch filters. Additionally, there are costs associated with CloudWatch and S3 for log storage. A simpler approach would be to use native MySQL capability to invoke the AWS Lambda function. Therefore, this is not the optimal solution.
Option D is incorrect because audit logs are exported to CloudWatch. Further, this is not an optimal solution as it involves complexity and costs associated with CloudTrail and SNS services.
Reference:
https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/AuroraMySQL.Integrating.Lambda.html