Case Assignment Rules are the standard Salesforce feature designed to automatically route incoming cases to the appropriate user or queue. These rules evaluate criteria on the case record, or related records like the Account, upon creation. In this scenario, the rule can be configured with two entries: one that checks if the Account Level is 'Platinum' and assigns the case to the 'Priority Support Queue', and a second entry that checks if the Account Level is 'Silver' or 'Gold' and assigns it to the 'Regular Support Queue'.

B. Case Rules: This is not a standard, recognized feature name in Salesforce. It is a distractor option that combines terms from other, valid features.

C. Workflow Rules: While Workflow Rules can automate actions upon record creation, they cannot directly change the owner of a case to a queue. Their primary actions are field updates, email alerts, task creation, and outbound messages.

D. Escalation Rules: Escalation Rules are time-based and are used to automatically reassign or notify stakeholders about cases that have not been resolved within a specified period, not for initial routing upon creation.

1. Salesforce Help, "Set Up Assignment Rules": "Use case assignment rules to automatically assign cases to users or queues based on criteria you define. A case assignment rule can have multiple rule entries. Each entry has an order, criteria, and the user or queue to assign the case to." This document explicitly states that Case Assignment Rules are used for this purpose.

2. Salesforce Help, "Guidelines for Setting Up Case Assignment Rules": "Case assignment rules let you automatically assign cases to the appropriate agent or team." This further reinforces that assignment rules are the correct tool for automatic routing.

3. Salesforce Help, "Case Escalation": "Case escalation rules automatically reroute a case and can notify a user if the case isn't closed within a specific time." This reference clarifies the purpose of Escalation Rules, distinguishing them from initial assignment.

4. Salesforce Help, "Workflow Rule Actions": This document outlines the four actions available for Workflow Rules: "New Task," "New Email Alert," "New Field Update," and "New Outbound Message." It confirms that changing record ownership to a queue is not a native action of Workflow Rules.