Who is accountable for managing the progress of work during a Sprint?

The Developers are accountable for managing the progress of work during a Sprint, as they are the ones who plan, execute, and deliver the work. The Scrum Guide states that "The Developers are the people in the Scrum Team that are committed to creating any aspect of a usable Increment each Sprint."1 The Developers are also responsible for conducting the Daily Scrum, a 15-minute event for the Developers to synchronize activities and create a plan for the next 24 hours.1 The Developers are self-managing, which means they decide how best to accomplish their work, rather than being directed by others outside the Scrum Team.1

References:

1: The Scrum Guide2, page 7

2: The Scrum Guide