The primary issue is the manual effort sales reps expend to grant access to a consistent group of supporting users for their accounts. Default Account Teams are designed specifically to automate this process. Each sales rep can pre-define their standard team of collaborators (legal, engineering, etc.) in their personal settings. When that rep creates a new account or becomes the owner of an existing one, their default team is automatically added to the Account Team. This grants the necessary record-level access to the support staff without requiring manual sharing for each record, directly improving the sales reps' productivity.

A. Create a criteria based sharing rule to grant access to other users.

This is incorrect because criteria-based sharing is driven by record attributes, not by the user who owns the record. It cannot dynamically build a team specific to each sales rep.

C. Create a permission set with View All Data and assign to supporting users.

This violates the principle of least privilege. "View All Data" grants access to all customer records, not just the specific ones where support is needed, creating a significant security risk.

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1. Salesforce Help, "Set Up a Default Account Team": "To save time and for consistency, you can set up a default account team of colleagues you typically work with on your accounts... When you create or own an account, your default team is automatically added to the account team." This directly supports the automation and productivity goal.

2. Salesforce Help, "Account Teams": "An account team is a team of users who work together on an account... An account team can include an executive sponsor, a dedicated support representative, and a project manager, for example." This confirms the feature's purpose is to manage access for collaborative teams like the one described.

3. Salesforce Security Guide, "Object-Level Security" (Page 10): The guide details administrative permissions like "View All" and "Modify All". It explains that these permissions override sharing rules and settings, granting access to all records of a specific object. This confirms that using "View All Data" (Option C) is an inappropriate and overly permissive solution for record-specific access.

4. Salesforce Architect's Handbook, "Record-Level Security": This resource often contrasts sharing mechanisms. It would position Account Teams as the appropriate solution for stable, user-centric, collaborative teams, whereas criteria-based sharing rules (Option A) are for broad, automated sharing based on record data, not team composition.