Sprint start

Hi,

as mentioned on the scrum guide, the sprint is ; All the work necessary to achieve the Product Goal, including Sprint Planning, Daily Scrums, Sprint Review, and Sprint Retrospective, happen within Sprints.

if you are speaking about the sprint execution it's Dev team if not so it's the scrum team.

Who will start the sprint? Is it Product Owner or Scrum Master?

If the last Sprint has finished, it's already started.

As @Ian points out, a Sprint starts by itself upon completion of the previous Sprint.  Who makes the formal announcement, pushes the appropriate buttons, or decides the time these events occur is a process question.  Since the Scrum framework does not dictate process, this falls back to your team to decide. 

This the second paragraph from the Scrum Guide's section that describes the Scrum Team.

Scrum Teams are cross-functional, meaning the members have all the skills necessary to create value each Sprint. They are also self-managing, meaning they internally decide who does what, when, and how.

So what does your Scrum Team say is the answer to your question?

i just registered for the PSM certification.

i have tried all the questions in the assessment tab and also the questions in scrum.org quiz.

kindly tell if this prep is enough to pass the test or are there other questions i can practice from