**Core Concept**
Carhart's notch is a characteristic finding on an audiogram, representing a depression in bone-conducted thresholds at 2,000 Hz. This phenomenon is associated with age-related hearing loss, particularly sensorineural hearing loss, and is often seen in individuals with otosclerosis.

**Why the Correct Answer is Right**
The presence of Carhart's notch is thought to be due to the abnormal bone conduction at 2,000 Hz, which is a result of the fixation of the stapes footplate in otosclerosis. This fixation leads to an increased stiffness of the ossicular chain, causing a mismatch between air and bone conduction thresholds. The resulting depression in bone-conducted thresholds at 2,000 Hz is known as Carhart's notch. This phenomenon is a key diagnostic feature in the evaluation of patients with suspected otosclerosis.

**Why Each Wrong Option is Incorrect**
* **Option A:** Carhart's notch is not typically seen in conductive hearing loss, which is more commonly associated with a rise in bone-conducted thresholds.
* **Option B:** While Carhart's notch can be seen in some cases of sensorineural hearing loss, it is not a characteristic feature of this condition.
* **Option C:** Carhart's notch is not associated with Meniere's disease, which is a disorder of the inner ear that affects balance and hearing.

**Clinical Pearl / High-Yield Fact**
Carhart's notch is a classic exam finding that can help differentiate otosclerosis from other causes of hearing loss. It is essential to recognize this phenomenon when interpreting audiograms in patients with suspected otosclerosis.

**Correct Answer: D. Otosclerosis**