## **Core Concept**
Reiter's syndrome, also known as reactive arthritis, is a form of seronegative spondyloarthritis that classically presents with a triad of symptoms. This condition often develops following a bacterial infection, typically after a gastrointestinal or genitourinary infection. The core concept being tested here involves the characteristic clinical features of Reiter's syndrome.

## **Why the Correct Answer is Right**
The classic triad of Reiter's syndrome consists of **conjunctivitis** (or uveitis), **urethritis**, and **arthritis**. This triad represents the hallmark symptoms that are commonly observed in patients with reactive arthritis. Conjunctivitis is often seen as a mild, non-specific conjunctivitis but can also present as more severe forms of eye inflammation. Urethritis presents with symptoms such as dysuria and discharge in men, though it can be asymptomatic. Arthritis typically involves asymmetric oligoarthritis, most commonly affecting the knees, ankles, and feet.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Conjunctivitis is a part of the classic triad of Reiter's syndrome.
- **Option B:** Urethritis is also a component of the triad.
- **Option D:** Arthritis is the third component of the classic triad.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that while the classic triad of conjunctivitis, urethritis, and arthritis is highly suggestive of Reiter's syndrome, not all patients present with all three symptoms simultaneously. The condition is strongly associated with HLA-B27, and patients may also exhibit other extra-articular manifestations such as skin lesions (psoriasis-like or keratoderma blennorrhagicum) and enthesitis.

## **Correct Answer:** .