I'd say B, An online platform for game creation. Millions of people can create their own game, clothes, and sometimes items on ROBLOX, for Millions of people to enjoy.
Honestly, ROBLOX isn't really like Minecraft, especially Survival. I'm not sure people always compare it.
And, the last 2 options C and D don't really fit ROBLOX. I wouldn't be able to guess you were talking about ROBLOX just hearing those choices.