If x and y are numbers such that (x+5)(y-5)=0, what is the smallest possible value of x^2 + y^2  Select the correct option:
A) 0
B) 4
C) 9
D) 25
E) 16

Rationale: "from ( x + 5 ) ( y - 5 ) = 0 it follows that either x = - 5 or y = 5 . thus either x ^ 2 = 25 or y ^ 2 = 25 . now , if x ^ 2 = 8125 , then the least value of y ^ 2 is 0 , so the least value of x ^ 2 + y ^ 2 = 25 + 0 = 25 . similarly if y ^ 2 = 25 , then the least value of x ^ 2 is 0 , so the least value of x ^ 2 + y ^ 2 = 0 + 25 = 25 . answer : d ."
Answer: D