The correct answer is A, because Development Team membership should change as needed, while taking into account a short term reduction in productivity. The Scrum Guide states that ''development Teams are cross-functional, with all of the skills as a team necessary to create a product Increment; development Teams are self-organizing. No one (not even the Scrum Master) tells the Development Team how to turn Product Backlog into Increments of potentially releasable functionality.'' Therefore, changing Development Team membership may affect their cross-functionality and self-organization in the short term.

According to the Scrum Guide1, the heart of Scrum is a Sprint, a time-box of one month or less during which a ''Done'', useable, and potentially releasable product Increment is created. The Increment is a concrete stepping stone toward the Product Goal. Each Increment is additive to all prior Increments and thoroughly verified, ensuring that all Increments work together.

According to the Scrum Guide1, ordering Product Backlog items is solely up to the Product Owner's discretion. The Product Owner orders items in the Product Backlog to best achieve goals and missions. To do this, they optimize value by considering various factors such as cost and benefit, risk, dependencies, date needed, etc. The Product Owner is responsible for maximizing the value of the work the Development Team does. 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. Therefore, an appropriate action for the Scrum Master to take if the Product Owner is struggling with ordering the Product Backlog is to offer the Product Owner help in understanding that the goal of ordering the Product Backlog is to maximize value.

The correct answer is B, because a product Increment does not have to be released to production at the end of each Sprint. The Scrum Guide states that ''at the end of a Sprint, the new Increment must be 'Done,' which means it must be in useable condition and meet the Scrum Team's definition of 'Done'. An increment is a body of inspectable, done work that supports empiricism at the end of the Sprint. The increment is a step toward a vision or goal.'' Therefore, a product Increment must be potentially releasable, but the decision to release it is up to the Product Owner.

According to the Scrum Guide, estimates are made by the people doing the work, which is the Development Team. The Development Team is responsible for all estimates in the Product Backlog and the Sprint Backlog. The other options are not valid guidelines for estimating work in Scrum, as they are either too prescriptive (such as requiring story points or relative units), incorrect (such as forbidding estimating or having the Product Owner make estimates), or unnecessary (such as checking estimates with the Development Team).