## **Core Concept**
The question involves understanding the relationship between hearing loss, pregnancy, and the type of hearing loss indicated by impedance audiometry. Impedance audiometry, also known as tympanometry, helps differentiate between conductive and sensorineural hearing losses and middle ear problems.

## **Why the Correct Answer is Right**
The patient's symptoms of bilateral hearing loss that worsened during pregnancy suggest otosclerosis. Otosclerosis is a condition characterized by abnormal bone growth in the middle ear that causes hearing loss. It often presents with conductive hearing loss and is known to worsen during pregnancy due to increased blood volume and changes in bone metabolism. The impedance audiometry graph for otosclerosis typically shows a **Type As** tympanogram, which indicates a stiff middle ear system. This is because the abnormal bone growth in otosclerosis leads to fixation of the stapes bone, reducing the mobility of the ossicles.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option does not correspond to the description of a Type As tympanogram. Without the images, we can infer based on standard tympanometry types: Type A is normal, Type Ad is highly compliant, Type As is a stiff middle ear system (as in otosclerosis), Type B is flat (as in fluid-filled middle ear), and Type C is indicative of Eustachian tube dysfunction.
- **Option B:** This would not represent the correct tympanogram type for otosclerosis.
- **Option D:** Similarly, this would not represent the tympanogram type associated with otosclerosis.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that otosclerosis often presents with conductive hearing loss that can worsen during pregnancy. A distinctive feature on impedance audiometry is the **Type As** tympanogram, which is crucial for diagnosing otosclerosis. Clinicians should consider otosclerosis in patients with progressive conductive hearing loss, particularly if it worsens during pregnancy.

## **Correct Answer:** .