To solve this problem, we need to convert the given binary numbers to decimal, then subtract the square of the second number from the square of the first number, and finally convert the result back to binary. (111two)2 in decimal is equal to (7)2 = 49. (101two)2 in decimal is equal to (5)2 = 25. Therefore, (111two)2 - (101two)2 = 49 - 25 = 24. Finally, we convert 24 to binary, which is 11000two. Therefore, the answer is option (D) 11000two.