What should Rob do in order to ensure a validation deployment for all Apex classes?

To ensure a validation deployment for all Apex classes, including validations for all profile deployments is a strategic approach because it ensures that any changes made to the Apex classes are compliant with the organization's best practices and coding standards as defined for each user profile. This means that when profiles are deployed, the associated Apex classes are also validated against any criteria that might affect how they interact with user permissions and field accessibility.

When profile deployments are validated, it checks that the Apex classes function correctly under the specific conditions dictated by the profiles. This comprehensive validation helps to catch any potential issues or errors early in the deployment process and ensures that the deployment does not lead to unexpected behaviors in production or conflicts with user access levels, which can be crucial in a multi-user environment.

While other choices might seem relevant, they don't provide the same level of thoroughness and oversight that validating profile deployments alongside Apex classes does. This strategy aligns with best practices in Salesforce development, where changes are tested in contexts that closely resemble their intended production environments.