B. would be my answer.
If not correct then go with A. (Communist dictatorship.)
The correct answer is D) Apportionment of legislative seats.
The Baker v. Carr case revolved around the case made by Republican Mayor of Millington, Tennessee (Charles Baker) who complained that the legislative districts in the state have now been redrawn in almost 60 years. This was a significant problem, as redistricting is supposed to take place every 10 years based on the new census data.