A separate Product Backlog is needed for every:(choose the best answer)

According to the Professional Scrum Product Owner™ II certification guide1, a Product Backlog is an ordered list of what is needed to improve the product. It is the single source of work undertaken by the Scrum Team. The Product Backlog is owned by the Product Owner, who is accountable for maximizing the value of the product resulting from the work of the Scrum Team. Therefore, a separate Product Backlog is needed for every product, not for every Scrum Team, portfolio, program, or all of the above. Multiple Scrum Teams can work on the same product and share the same Product Backlog2. A portfolio or a program may consist of multiple products, each with its own Product Backlog3. References: 1: Professional Scrum Product Owner™ II Certification | Scrum.org 2: What is a Product Backlog? | Scrum.org 3: Product Backlog Explained [+ Examples] | Atlassian