To solve this problem, we need to analyze the given statements about Klinefelter's Syndrome:$\newline \bullet$A. This disorder was first described by Langdon Down (1866).$\newline$ - This statement is incorrect. Klinefelter's Syndrome was first described by Dr. Harry Klinefelter in 1942, not by Langdon Down.$\newline \bullet$B. Such an individual has overall masculine development. However, the feminine development is also expressed.$\newline$ - This statement is correct. Individuals with Klinefelter's Syndrome typically have male physical characteristics but may also exhibit some female traits, such as breast development.$\newline \bullet$C. The affected individual is short statured.$\newline$ - This statement is incorrect. Individuals with Klinefelter's Syndrome are often taller than average.$\newline \bullet$D. Physical, psychomotor and mental development is retarded.$\newline$ - This statement is incorrect. While there may be some learning difficulties, the term "retarded" is outdated and not accurate for describing the condition.$\newline \bullet$E. Such individuals are sterile.$\newline$ - This statement is correct. Individuals with Klinefelter's Syndrome are typically sterile due to impaired testicular function.$\newline$Now, let's identify the correct statements:$\newline$B and E are correct.$\newline$Therefore, the correct answer is Option 3: B and E only.