According to the Scrum Guide 1 , each event in Scrum is a formal opportunity to inspect and adapt something. These events are specifically designed to enable critical transparency and inspection. Failure to include any of these events results in reduced transparency and is a lost opportunity to inspect and adapt. All events are time-boxed events, such that every event has a maximum duration. Once a Sprint begins, its duration is fixed and cannot be shortened or lengthened. The remaining events may end whenever the purpose of the event is achieved, ensuring an appropriate amount of time is spent without allowing waste in the process. The time-boxed events in Scrum are:
* Sprint Planning (eight hours or less for a one-month Sprint)
* Daily Scrum (15 minutes or less for a one-month Sprint)
* Sprint Review (four hours or less for a one-month Sprint)
* Sprint Retrospective (three hours or less for a one-month Sprint)
The other options are not time-boxed events in Scrum.
References: Scrum Guide

The correct answer is B, because the time-box for the Sprint Planning meeting is 8 hours for a monthly Sprint.
The Scrum Guide states that "Sprint Planning is time-boxed to a maximum of eight hours for a one-month Sprint. For shorter Sprints, the event is usually shorter."

According to the Scrum Guide, a Scrum Team must release each Increment when it makes sense to do so, based on the value and feedback obtained from stakeholders. The decision to release an Increment is made by the Product Owner, who is responsible for maximizing the value of the product and the work of the Development Team. The other options are not valid, as they imply that releasing an Increment is either mandatory (such as after every Sprint), conditional (such as when the product is free of defects), or irrelevant (such as when the Scrum Team finishes their work).

According to the Scrum Guide 1 , the Developers are self-organizing and decide how to turn Product Backlog items into an Increment of value. No one tells them how to do their work. The Developers are accountable for creating a plan for the Sprint, the Sprint Backlog. 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, when the Scrum Team gets caught in an internal disagreement about which development techniques to apply, two techniques that the Scrum Master could use are:
* Involve the complete Development Team, as they are responsible for managing and refining their own work.
* Use coaching techniques, such as open questions and active listening, to help the Development Team resolve their conflict and reach a consensus.
The other options are not appropriate, as they may undermine the self-organization and empowerment of the Developers.
References: Scrum Guide

According to the Scrum Guide, when many Scrum Teams are working on a single product, they must have a Definition of Done that makes their combined work potentially releasable. This ensures that there is a clear and consistent understanding of what "Done" means for the product and that there is no technical debt or unfinished work at the end of each Sprint. The other options are not valid descriptions of the Definition of Done for multiple Scrum Teams, as they either create inconsistency, confusion, or waste (such as having different definitions, discussing and reconciling differences during a hardening Sprint, or having the Scrum Masters define a common Definition of Done).