What should the SysOps administrator do to meet this requirement?

Explanations:

While adding a wait condition might seem like a solution, it does not guarantee that the RDS instance is created before the EC2 instance. The wait condition is primarily used for waiting on resource signals, not for resource dependency management. This option does not directly address the requirement of ensuring that the DB instance is provisioned before the EC2 instance.

The DependsOn attribute explicitly defines the creation order of resources. By adding DependsOn to the EC2 instance resource and specifying the logical name of the RDS resource, the CloudFormation template will ensure that the RDS instance is fully created before the EC2 instance starts launching. This directly meets the requirement of establishing the correct resource dependency.

Changing the order of resources in the template does not guarantee the creation sequence. AWS CloudFormation does not enforce a specific order based solely on the order of resources listed in the template unless explicitly defined using DependsOn. Thus, simply rearranging resources may not ensure that the RDS instance is created before the EC2 instance.

Creating multiple templates and using StackSets is an overcomplicated solution for this scenario. It introduces unnecessary complexity and does not directly address the requirement of ensuring the DB instance is created before the EC2 instance within a single stack. CloudFormation is designed to manage resource dependencies within a single template effectively, making this option inefficient.