:

• Option B is Correct: Klinefelter's Syndrome is caused by an additional copy of the X-chromosome (47, XXY). The affected individual has overall masculine development, but feminine development (e.g., development of breast or Gynaecomastia) is also expressed, and they are sterile .
• Options A, C, and D are Incorrect: These are characteristics of Down's Syndrome. Down's Syndrome was described by Langdon Down (1866), and affected individuals are short statured with retarded physical, psychomotor, and mental development .