New York City’s public schools do the best job among the nation’s largest school districts in offering students choice in where they attend classes, an analysis says.

The Brookings Institution’s "Education Choice and Competition Index" has awarded grades to the 25 largest school systems. None of the districts received an A or an F. New York City earned a B, as did Chicago. The lowest grade, a D, went to the Orange County (Fla.) District.

The index measured school districts in 13 categories "that are thought by experts to be important to the availability and quality of choice and to the extent to which choice creates competition" among schools, the institution says.

A key category that the index measures is how students are assigned to the schools they attend. Other categories include the availability of alternative schools; the process districts use for having students apply to a school; whether a district has a process for restructuring or closing an underperforming school; and districts’ policies on virtual education.