**Core Concept**
Klinefelter syndrome is a genetic condition in males characterized by an extra X chromosome, resulting in XXY instead of the typical XY karyotype. This condition is associated with various physical and developmental abnormalities.

**Why the Correct Answer is Right**
The diagnosis of Klinefelter syndrome is typically made through karyotyping, which involves analyzing the patient's chromosomes. Karyotyping can be performed on a variety of samples, including blood, bone marrow, or skin cells. In individuals with Klinefelter syndrome, the presence of an extra X chromosome (XYX) is a characteristic finding. This can be detected using techniques such as G-banding or fluorescence in situ hybridization (FISH).

**Why Each Wrong Option is Incorrect**
**Option A:** Karyotyping is not the only method used to diagnose Klinefelter syndrome, but it is the most definitive. Other methods, such as molecular genetic testing, may also be used.
**Option B:** While physical examination and medical history can provide clues suggesting Klinefelter syndrome, they are not diagnostic on their own.
**Option C:** Hormonal profiles may be abnormal in individuals with Klinefelter syndrome, but this is not a diagnostic criterion.

**Clinical Pearl / High-Yield Fact**
Klinefelter syndrome is the most common sex chromosome disorder, affecting approximately 1 in 650 males. It is often diagnosed in adolescence or early adulthood, although some cases may be identified in childhood.

**Correct Answer:** D. Karyotyping