**Core Concept**
Klinefelter's syndrome is a genetic disorder affecting males, characterized by the presence of an extra X chromosome (XXY), leading to various physical and developmental abnormalities.

**Why the Correct Answer is Right**
Klinefelter's syndrome is caused by the non-disjunction of sex chromosomes during meiosis, resulting in the formation of an XXY karyotype. This condition is associated with hypogonadism, infertility, and an increased risk of autoimmune disorders, cardiovascular disease, and certain cancers. The extra X chromosome leads to the overexpression of X-linked genes, disrupting the normal balance of sex hormones, particularly testosterone.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is often incorrect, as it doesn't specify the correct characteristics of Klinefelter's syndrome.
**Option B:** This option might be incorrect, as it doesn't accurately describe the genetic basis of Klinefelter's syndrome.
**Option C:** This option is incorrect, as it describes a different genetic condition.

**Clinical Pearl / High-Yield Fact**
One key aspect of Klinefelter's syndrome is the presence of hypergonadotropinism, characterized by elevated levels of follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which is essential for the diagnosis and management of this condition.

**Correct Answer: D.**