**Core Concept**
The patient described in the scenario is exhibiting symptoms of Obsessive-Compulsive Disorder (OCD), characterized by recurring, intrusive thoughts (obsessions) and repetitive behaviors (compulsions) aimed at reducing anxiety. Effective treatment of OCD requires medications that modulate serotonin levels in the brain.

**Why the Correct Answer is Right**
The correct answer is a Selective Serotonin Reuptake Inhibitor (SSRI), which is the first-line treatment for OCD. SSRIs work by increasing the levels of serotonin in the synaptic cleft by inhibiting the reuptake of serotonin into the presynaptic neuron. This increases the availability of serotonin for binding to postsynaptic receptors, leading to a decrease in obsessive thoughts and compulsive behaviors. Examples of SSRIs include fluoxetine and sertraline.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because while benzodiazepines can provide short-term relief for anxiety, they are not effective in treating the underlying symptoms of OCD. They can also lead to dependence and withdrawal symptoms upon discontinuation.
* **Option B:** This option is incorrect because mood stabilizers, such as lithium, are used to treat bipolar disorder and are not indicated for the treatment of OCD.
* **Option C:** This option is incorrect because antipsychotics, such as haloperidol, may be used to treat the behavioral symptoms of OCD but are not the first-line treatment and can have significant side effects, including extrapyramidal symptoms.

**Clinical Pearl / High-Yield Fact**
SSRIs are effective in treating OCD because they increase the levels of serotonin in the brain, which helps to reduce the frequency and intensity of obsessive thoughts and compulsive behaviors. It's essential to note that SSRIs can take several weeks to become effective, and patients may require a trial of multiple medications before finding the right one.

**Correct Answer:** C.