Which of the following affect the outcome of a Sprint?

The complexity of the problem being solved and the complexity of the requirements are both sources of uncertainty and variability that can impact the Sprint Goal and the Sprint Backlog. The skills and working relationships of the people on the Scrum Team(s) are also crucial for delivering a valuable product increment in a Sprint. The Scrum Master is accountable for establishing an environment where the Scrum Team can be effective and improving the professionalism of the Scrum Team.

References:

Scrum Guide 2020, page 6: “The Scrum Master is accountable for establishing Scrum as defined in the Scrum Guide. They do this by helping everyone understand Scrum theory and practice, both within the Scrum Team and the organization.”

Scrum Guide 2020, page 10: “The Sprint Goal is an objective set for the Sprint that can be met through the implementation of Product Backlog items. This provides guidance to the Development Team on why it is building the Increment.”

Scrum Guide 2020, page 11: “The Sprint Backlog is composed of the Sprint Goal (why), the set of Product Backlog items selected for the Sprint (what), as well as an actionable plan for delivering the Increment (how).”

Evidence-Based Management Guide, page 9: “Uncertainty is inherent in complex work. The more complex work is, the more uncertainty there is.Uncertainty comes from two sources: variability and emergence.”