Answer:-2. How much is known about the Product over time

For Note:-
The Cone of Uncertainty describes the evolution of the amount of uncertainty during a project.

Answer:-3. A small team of people that is highly flexible and adaptive

For Note:-
The essence of Scrum is a small team of people. The individual team is highly flexible and adaptive. These strengths continue operating in single, several, many, and networks of teams that develop, release, operate and sustain the work and work products of thousands of people. They collaborate and interoperate through sophisticated development architectures and target release environments.

Answer:-4. Any technique, even a mix of several techniques

For Note:-
User stories are a fairly common technique for representing Product Backlog Items, but other techniques can be used instead. For instance, a team can use scenarios, use cases, acceptance tests, etc. The Product Backlog might even contain a heterogeneous mix of the above. The Product Owner should work with the rest of the Scrum Team on choosing and optimizing the techniques used to represent Product Backlog Items.

Answer:-(3) and (4)

For Note:-
The Product Owner is the sole person responsible for the Product Backlog. However, he or she can delegate some work related to product backlog management to the Development Team.

Answer:-1. The Product Backlog items selected for this Sprint plus the plan for delivering them

For Note:-
The Sprint Backlog is the set of Product Backlog items selected for the Sprint, plus a plan for delivering the product Increment and realizing the Sprint Goal.