Explanation
Lead and Case are two objects that support creating queues. Queues are used to route records to a group of users who share workloads. Queues are available for standard objects such as Lead and Case, and custom objects that have a queue-supported lookup field. Option A is incorrect, since Account does not support creating queues. Option B is incorrect, since Opportunity does not support creating queues.

The Opportunity Team feature is the most effective way to collaborate on an opportunity in a private sharing model. By adding the product specialist and solution engineer to the Opportunity Team, the junior account manager can share specific permissions for the opportunity without altering ownership. Additionally, Opportunity Team settings remain intact even if the account ownership changes to a senior manager.
* Option A: Manual sharing is less flexible and requires re-sharing if the account is reassigned.
* Option B: Sharing the account doesn't ensure access to opportunities since sharing is record-specific in a private model.
* Option C (Correct): Opportunity Teams allow role-based collaboration and persistent sharing, ensuring access is unaffected by ownership changes.
References:
* Opportunity Team Overview

Explanation
Content delivery is a feature that allows users to share files with customers and protect them with a password.
Setting up an experience cloud site would require additional configuration and licensing. Utilizing an AppExchange product would introduce a dependency on a third-party solution.