In the DSM-5, phobic disorders fall under the category of Anxiety disorders. Anxiety disorders encompass a range of conditions characterized by excessive fear or anxiety. Phobic disorders specifically involve intense and irrational fears of specific objects or situations, leading to avoidance behaviors. Examples include specific phobias like fear of heights (acrophobia) or fear of spiders (arachnophobia).
So, the correct answer to the question is:
O Anxiety disorder.