Which solution will accomplish this with the LEAST amount of development effort?

Create an Amazon CloudWatch Event rule that runs periodically and targets an AWS Lambda function. Within the Lambda function, evaluate the current state of the AWS environment and compare deployed resource values to resource limits on the account. Notify the senior manager if the account is approaching a service limit.

Deploy an AWS Lambda function that refreshes AWS Trusted Advisor checks, and configure an Amazon CloudWatch Events rule to run the Lambda function periodically. Create another CloudWatch Events rule with an event pattern matching Trusted Advisor events and a target Lambda function. In the target Lambda function, notify the senior manager.

Deploy an AWS Lambda function that refreshes AWS Personal Health Dashboard checks, and configure an Amazon CloudWatch Events rule to run the Lambda function periodically. Create another CloudWatch Events rule with an event pattern matching Personal Health Dashboard events and a target Lambda function. In the target Lambda function, notify the senior manager.

Add an AWS Config custom rule that runs periodically, checks the AWS service limit status, and streams notifications to an Amazon SNS topic. Deploy an AWS Lambda function that notifies the senior manager, and subscribe the Lambda function to the SNS topic.