**Core Concept**
A vesicular mole, also known as a hydatidiform mole, is a type of gestational trophoblastic disease characterized by abnormal trophoblastic proliferation and villous hydropic degeneration. The diagnosis of a vesicular mole is confirmed through histopathological examination of the uterine contents.

**Why the Correct Answer is Right**
The correct answer is **C. Histopathological examination of the uterine contents**. This is because a vesicular mole is a clinical diagnosis that requires histopathological confirmation. The histopathological features of a vesicular mole include villous edema, trophoblastic proliferation, and the absence of fetal parts. The examination of the uterine contents, which typically includes a dilatation and curettage (D&C), provides the necessary tissue sample for histopathological analysis.

**Why Each Wrong Option is Incorrect**
**Option A:** Ultrasound examination, while helpful in suggesting the diagnosis of a vesicular mole, is not sufficient for confirmation. Ultrasound findings may include the presence of a hyperechoic mass, but they do not provide definitive evidence of the diagnosis.

**Option B:** Human chorionic gonadotropin (hCG) levels are elevated in a vesicular mole, but they are not specific for the diagnosis. Elevated hCG levels can be seen in other conditions, such as choriocarcinoma or normal pregnancy.

**Clinical Pearl / High-Yield Fact**
A key feature of a vesicular mole is the absence of fetal parts on histopathological examination. This is in contrast to a normal pregnancy, where fetal parts are present in the uterine contents.

**Correct Answer: C. Histopathological examination of the uterine contents**