The Sprint Backlog is the Developers' plan for the Sprint. According to the 2020 Scrum Guide, the Sprint Backlog is composed of:

The Sprint Goal

The Product Backlog Items selected for the Sprint

An actionable plan for delivering the Increment

Because Scrum does not prescribe a specific format for Product Backlog Items or for the detailed plan inside the Sprint Backlog, several kinds of items may appear there.

Why A is correct -- User Stories:

Scrum does not require User Stories, but if the selected Product Backlog Items are written as User Stories, then they may be included in the Sprint Backlog. User Stories are a common technique, not a Scrum requirement.

Why B is correct -- Tests:

Tests may absolutely be part of the actionable plan for delivering an Increment. If testing work is needed to meet the Definition of Done, it can be represented in the Sprint Backlog.

Why C is correct -- Tasks:

Tasks are a common way Developers break down work in the Sprint Backlog. Scrum does not require tasks, but they may be used as part of the Developers' plan.

Why D is correct -- Additional decomposition items:

This is directly aligned with Scrum thinking. The Sprint Backlog may contain additional items that decompose the selected Product Backlog Items into actionable work.

Why E is correct -- Use Cases:

Like User Stories, Use Cases are not required by Scrum, but they may be used if that is how the team expresses selected Product Backlog Items or supporting detail for Sprint work.

Key Scrum point:

Scrum defines the purpose and content of the Sprint Backlog, but it does not force teams to use only one documentation style. Therefore, all of these items may be included.

2020 Scrum Guide -- Sprint Backlog: https://scrumguides.org/scrum-guide.html#sprint-backlog

2020 Scrum Guide -- Sprint Planning: https://scrumguides.org/scrum-guide.html#sprint-planning

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