**Core Concept**
Olopatadine is an antihistamine medication used to treat allergic conjunctivitis and rhinitis. It belongs to the class of drugs known as antihistamines, which work by blocking the action of histamine, a chemical released during allergic reactions.

**Why the Correct Answer is Right**
Olopatadine acts as a non-selective histone deacetylase inhibitor (HDACi) and a selective histamine H1 receptor antagonist. By blocking the histamine H1 receptor, olopatadine reduces the symptoms of allergic reactions, such as itching, sneezing, and congestion. Additionally, its HDAC inhibitory activity has been implicated in its anti-inflammatory effects.

**Why Each Wrong Option is Incorrect**
**Option A:** Olopatadine is not a corticosteroid, which is a different class of anti-inflammatory medication.
**Option B:** Olopatadine does not act as a selective serotonin reuptake inhibitor (SSRI), which is a class of antidepressant medication.
**Option C:** Olopatadine does not act as a non-selective beta-adrenergic receptor antagonist, which is a class of medication used to treat hypertension and heart failure.

**Clinical Pearl / High-Yield Fact**
Olopatadine's unique dual mechanism of action as both an antihistamine and an HDAC inhibitor sets it apart from other antihistamines and makes it a valuable treatment option for patients with allergic conjunctivitis and rhinitis.

**Correct Answer:** C.