SAT Right Triangles - Pythagorean Theorem

Geometry

Which of the following CANNOT be the lengths of the sides of an obtuse triangle?

(A) $\ \ 5, 6, 10$
(B) $\ \ 6, 6, 6\sqrt{2}$
(C) $\ \ 6, 8, 11$
(D) $\ \ 10, 15, 20$
(E) $\ \ 20n, 30n, 40n$