According to the Scrum Guide, the Scrum Master is responsible for coaching the Scrum Team to improve its skills, tools and environment over time and adjust the Definition of Done accordingly1. The Definition of Done is a formal description of the state of the Increment when it meets the quality measures required for the product1. The Definition of Done should be possible to achieve given current circumstances2. Therefore, option B and E are appropriate for a Scrum Master to do, if the Scrum Team does not have the tools and environment to completely finish each selected Product Backlog item.

Option A is not appropriate because declaring the Scrum Team not ready for Scrum implies that there is a fixed set of prerequisites for using Scrum, which is not true. Scrum is a framework that can be applied to any complex product development effort1.

Option C is not appropriate because encouraging the Product Owner to accept partially done Increments until the situation improves violates the principle of transparency. Transparency requires that the Increment is a usable product that meets the current Definition of Done1. Accepting partially done Increments also increases technical debt and reduces value delivery3.

Option D is not appropriate because refocusing the current Sprint on establishing the Scrum Team’s environment instead of delivering an Increment goes against the purpose of a Sprint. A Sprint is a time-boxed event that serves as a container for the other Scrum events and activities. The goal of each Sprint is to deliver a potentially releasable Increment that adheres to the current Definition of Done1.

References: 1: The Scrum Guide 2: Suggested Reading for Professional Scrum Master™ I 3: Mastering Professional Scrum