According to the Scrum Guide1, 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-box for the Sprint Review is four hours for a one-month Sprint.

According to the Scrum Guide1, 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.

During the Sprint, the Scrum Master's role is to facilitate inspection and adaptation opportunities as requested or needed, and to coach the team members in self-management, as stated in 3: "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. The Scrum Master is accountable for the Scrum Team's effectiveness. They do this by enabling the Scrum Team to improve its practices, within the Scrum framework."

Scrum is not a process, technique, or definitive method. Rather, it is a framework within which you can employ various processes and techniques. Scrum makes clear the relative efficacy of your product management and work techniques so that you can continuously improve the product, the team, and the working environment.

According to the Scrum Guide, multiple Scrum Teams working on the same product do not have to have the same Sprint start date. They may start their Sprints at different times, as long as they synchronize their work and integrate their Increments at least by the end of each Sprint. The other option is not valid, as it implies that having the same Sprint start date is mandatory for multiple Scrum Teams.