From the Perspective of the Textbook, Which One of the Following

From the perspective of the textbook, which one of the following classrooms best illustrates effective classroom management?

A) While Mr.Alton works with a reading group, most of his other students are doing their assigned seatwork, although a handful of them are giggling in the corner about something that happened in the lunchroom earlier.
B) In his physical education class, Mr.Berg works with the students who seem truly interested in learning the long jump.Those students who don't want to try the jump are allowed to sit on the sidelines and talk quietly among themselves.
C) While Ms.Carrera sits at her desk in the front of the classroom, her students are doing assignments independently at their desks.As long as the classroom is quiet, she overlooks the whispering, note passing, and mindless doodling that is occurring.
D) Ms.Demaine's students are busily working on their math assignments in groups of three or four students each.The classroom gets a bit noisy at times when a group disagrees about how to do a problem.