**Core Concept**
Obsessive-compulsive disorder (OCD) is a chronic mental health condition characterized by recurring, intrusive thoughts (obsessions) and repetitive behaviors (compulsions). The condition is often treated with a combination of psychotherapy and pharmacotherapy, focusing on reducing symptoms of anxiety and improving quality of life.

**Why the Correct Answer is Right**
Selective serotonin reuptake inhibitors (SSRIs) are a class of medications commonly used to treat OCD. SSRIs increase the levels of serotonin in the brain by preventing its reabsorption, thereby reducing symptoms of anxiety and improving mood. The mechanism of action involves the inhibition of the serotonin transporter protein, which is responsible for the reuptake of serotonin from the synaptic cleft. This leads to increased postsynaptic serotonin levels, which in turn modulates the activity of various neurotransmitter systems involved in anxiety and mood regulation.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because tricyclic antidepressants (TCAs) are not typically used as first-line treatment for OCD due to their side-effect profile and potential for toxicity.
**Option B:** This option is incorrect because benzodiazepines are not effective in treating the underlying symptoms of OCD and can even exacerbate anxiety in the long term.
**Option C:** This option is incorrect because antipsychotics are not the primary treatment for OCD, although they may be used in combination with SSRIs in some cases.

**Clinical Pearl / High-Yield Fact**
SSRIs are a preferred treatment for OCD due to their efficacy, tolerability, and relatively favorable side-effect profile compared to other classes of medications.

**Correct Answer: C. Fluoxetine**