We have to use Pythagorean Theorem to solve this. We square the two smallest sides, then add. If the sum is the square of the largest side, then it's our answer.
A. 7, 9, 11
49 + 81 = 130 ≠ 121
B. 12, 18, 22
144 + 324 = 468 ≠ 484
C. 10, 15, 20
100 + 225 = 325 ≠ 400
D. 8, 15, 17
64 + 225 = 289 = 289
So, our answer is D