**Core Concept**
Tympanometry is a test used to assess the function and mobility of the eardrum and the middle ear system. It involves the insertion of a tympanometer probe into the ear canal, which measures the movement of the eardrum in response to changes in air pressure. The resulting graph provides information about the middle ear's ability to conduct sound.

**Why the Correct Answer is Right**
The graph in question is likely to show a flat tympanogram, which indicates a non-compliant middle ear system, often due to Eustachian tube dysfunction or ossicular discontinuity. During pregnancy, hormonal changes can lead to Eustachian tube dysfunction, causing middle ear pressure imbalances. This can result in conductive hearing loss, as seen in this patient.

**Why Each Wrong Option is Incorrect**
* **Option A:** A tympanogram with a peak in the positive pressure range, indicating normal middle ear function, would not be consistent with the patient's symptoms of hearing loss.
* **Option B:** A tympanogram with a peak in the negative pressure range, indicating a perforated eardrum or ossicular discontinuity, would not be the most likely explanation for the patient's symptoms, given her age and the fact that her hearing loss worsened during pregnancy.
* **Option C:** A tympanogram with a high compliance peak, indicating a normal eardrum and middle ear system, would not be consistent with the patient's symptoms of hearing loss.

**Clinical Pearl / High-Yield Fact**
Tympanometry is a useful tool for diagnosing middle ear problems, including Eustachian tube dysfunction, which can be exacerbated by pregnancy. It's essential to consider the patient's medical history and symptoms when interpreting tympanometry results.

**Correct Answer:** B.