Set A of 8 positive integers may have the same element and have 39. And set B of 8 positive integers must have different elements and have 39. When m and n are the greatest possible differences between 39 and other elements’ sums in set A and set B, respectively, m-n=? Choose the correct choice from the following answers.
A) 20	B) 23	C) 21	D) 25	E) 26

Rationale: this is maximum - minimum . hence , 39 - ( 1 + 1 + 1 + 1 + 1 + 1 + 1 ) = 32 and 39 - ( 1 + 2 + 3 + 4 + 5 + 6 + 7 ) = 11 . so , 32 - 11 = 21 . the correct answer is c .
Answer: C