Which tool should Universal Containers use to migrate functionality from the sandbox to the production environment?

The correct choice highlights a comprehensive suite of tools specifically designed for migrating functionality and metadata from a sandbox to a production environment within Salesforce. The Force.com migration tool is particularly noteworthy as it allows developers to deploy metadata and code from a local directory to Salesforce environments, making it especially suitable for more complex migrations.

Additionally, the Force.com IDE (Integrated Development Environment) provides a user-friendly interface for developers to manage their Salesforce applications and can be utilized for developing, debugging, and deploying applications. It helps streamline the deployment process for various components, such as Apex classes and Visualforce pages.

Change sets are also essential in this context. They provide a way to package and deploy changes made in the sandbox (like new custom objects, fields, and other configuration settings) directly to the production environment without the need for advanced coding knowledge. This is particularly useful for administrators who may not be familiar with using development tools.

Together, these tools cover a wide range of migration tasks, from coding to configuration, making the selected option the most effective choice for moving functionality from development to a live environment.