I wish to restrict the user posting a new article to select only 1 category for that post. It doesn't matter which category he chooses as long as he chooses just one. This way posts are maintained under a hierarchy (and I want to avoid users clicking all categories so that their posts appear everywhere).
I don't want to restrict the user to a specific category, I just want to limit the number of categories the user can choose for a post to 1.
Is there any way to achieve this in Wordpress?