Answer:
I believe the answer is B
Explanation:
[B], developing the art style guide and production plan.
It wouldn't be [A], because patches are released to consumers of the game, to fix bugs and add new content, which won't be done until post-production.
It wouldn't be [C] either, as it is also post-production, because you are sending the game to produced, packaged and shipped, meaning the game has already been pretty much fully developed.
