B. SEGA
Sonic is the most recognizable SEGA character because although he could technically be included in Nintendo, I think most people would say the most recognizable character from Nintendo would be Mario. Playstation wouldn't be the answer because Playstation is more of a provider for the game. You can buy stuff like "Sonic and SEGA All-Stars Racing" on Playstation and the same goes to Microsoft where it's really only a provider of games from SEGA including Sonic. Nintendo would also be a provider but with the help of SEGA, Nintendo does make a few games here and there with Sonic's likeness included. (They might use Sonic as an extra character in a video game.)