A prominent think tank gave Cobb County’s school system a C grade for its efforts to provide educational choices, such as access to charter schools, online courses and magnet schools.

The Washington, D.C.-based Brookings Institution’s annual Education Choice and Competition Index gave Cobb, the state’s second-largest school district, high marks for accesibility to online courses, but handed out low scores in areas like “degree of choice and fairness in school assignment.” The report was released Thursday.

The index rated Cobb 25th out of 112 school districts surveyed nationwide. Cobb was the highest rated Georgia school district in the report.

Brookings used federal education data, responses from surveys sent to the districts and other research to help compile its findings. Brookings did not discuss the findings with the districts before they were released.