**Core Concept**
The head impulse test (HIT) is a clinical assessment tool used to evaluate the vestibulo-ocular reflex (VOR) and diagnose peripheral vestibular disorders, particularly benign paroxysmal positional vertigo (BPPV).

**Why the Correct Answer is Right**
The head impulse test assesses the vestibulo-ocular reflex by rapidly moving the head and observing the eye movements. In patients with peripheral vestibular disorders, the VOR is impaired, leading to an abnormal head impulse response. The test is particularly useful in diagnosing BPPV, where the abnormal eye movements are characterized by a catch-up saccade. The HIT is performed by having the patient look at a target and then rapidly moving their head to the side, while the examiner observes the eye movements.

**Why Each Wrong Option is Incorrect**
**Option A:** The Dix-Hallpike test is used to diagnose BPPV, but it is not the same as the head impulse test.
**Option B:** The caloric test is used to assess the vestibular function, but it is not a specific diagnostic test for BPPV.
**Option C:** The electronystagmography (ENG) test is a more comprehensive assessment of the vestibular system, but it is not a bedside test like the HIT.

**Clinical Pearl / High-Yield Fact**
The head impulse test is a quick and easy bedside test that can be performed in any clinical setting to diagnose peripheral vestibular disorders, making it a valuable tool in the diagnosis of BPPV.

**Correct Answer: C. Peripheral vestibular disorders.**