\[M( - 4;\ 5),\ N( - 10;\ 7),\ K(8;\ 1):\]
\[MN = \sqrt{( - 4 + 10)^{2} + (5 - 7)^{2}} =\]
\[= \sqrt{36 + 4} = 2\sqrt{10};\]
\[NK = \sqrt{( - 10 - 8)^{2} + (7 - 1)^{2}} =\]
\[= \sqrt{324 + 36} = 6\sqrt{10};\]
\[MK = \sqrt{( - 4 - 8)^{2} + (5 - 1)^{2}} =\]
\[= \sqrt{144 + 16} = 4\sqrt{10};\]
\[NK = MN + MK.\]
\[Ответ:\ \ M.\]