Explanation
A "Quality Assurance and Release Readiness Sprint" is not a Scrum concept, but a sign of poor engineering practices and weak adherence to the Scrum values and principles. It indicates that the Scrum Team is not delivering a potentially releasable product Increment every Sprint, which is one of the core commitments of Scrum. This could be due to a weak or incomplete Definition of Done, which allows technical debt to accumulate and compromises the quality and usability of the product. It could also be due to the Developers finding it nearly impossible to create a valuable, useful product Increment in a Sprint, which could be caused by various factors such as lack of skills, tools, collaboration, feedback, or empowerment. The Definition of Done is not being met every Sprint, which means that the Scrum Team is not fulfilling its accountability for the Increment and is not transparent about the state of the product.
References:
Scrum Guide 2020, section "Commitments", "Definition of Done", "The Sprint", "The Increment".
Advanced Knowledge of Scrum, section "Definition of Done", "Technical Debt".
Scrum Master Accountabilities, section "Accountability for Effectiveness".

Scrum is a framework with built in flexibility to support multiple Scrum Teams working on a single product.

One of the primary responsibilities of a Scrum Master is the ability to facilitate regardless of the context or setting.

The number of items selected from the Product Backlog for the Sprint is solely up to the Development Team. Only the Development Team can assess what it can accomplish over the upcoming Sprint.
The Sprint Goal is an objective set for the Sprint that can be met through the implementation of Product Backlog. It provides guidance to the Development Team on why it is building the Increment. It is created during the Sprint Planning meeting. The Sprint Goal gives the Development Team some flexibility regarding the functionality implemented within the Sprint. The selected Product Backlog items deliver one coherent function, which can be the Sprint Goal. The Sprint Goal can be any other coherence that causes the Development Team to work together rather than on separate initiatives.

This approach ensures that the Product Backlog items are ready for the Sprint Planning and that the Developers can focus on their work during the Sprint. It also allows the Product Owner to collaborate with the stakeholders and align the Product Backlog with the Product Goal. The other options are either inefficient, ineffective, or not aligned with the Scrum values and principles