Obsessive-compulsive disorder (OCD) involves which of the following?

Obsessive-compulsive disorder (OCD) is characterized by the presence of unwanted, persistent thoughts—often referred to as obsessions—and repetitive actions or rituals—known as compulsions. Individuals with OCD often experience significant anxiety due to these intrusive thoughts, which they feel compelled to alleviate through certain behaviors. For instance, a person may have obsessive thoughts about contamination and feel driven to wash their hands repeatedly to reduce that anxiety.

The other options describe different types of anxiety disorders or phenomena. Fear of social interactions is characteristic of social anxiety disorder, while extreme fear of the environment is not typically associated with OCD but could relate to phobias. Lastly, anxiety derived from separation is indicative of separation anxiety disorder, which focuses on distress when separated from attachment figures. Thus, the correct option accurately encapsulates the fundamental aspects of OCD.