Klinefelter's syndrome is characterized by which of the following chromosomal patterns?

Klinefelter's syndrome is characterized by the presence of at least one extra X chromosome in males, resulting in a chromosomal pattern of 47, XXY. This genetic condition arises from nondisjunction during meiosis, leading to the inclusion of an additional X chromosome. Individuals with Klinefelter's syndrome typically exhibit features such as tall stature, gynecomastia, and infertility, which are associated with the disruptions in normal testosterone production and secondary sexual characteristics.

The 45, X configuration refers to Turner syndrome, which affects females and is characterized by the absence of one X chromosome. The 46, XY pattern represents typical male karyotype without any chromosomal abnormalities. Lastly, 47, XXX describes a condition often referred to as Triple X syndrome, which affects females and involves an extra X chromosome without the specific features associated with Klinefelter's syndrome. Therefore, the chromosomal pattern that identifies Klinefelter's syndrome is clearly 47, XXY.