To represent a right triangle, you would need to use the Pythagorean theorem to find out which one makes up a right triangle and which one doesn't. 6^2 and 8^2 together make up 100 or 10^2 in which A isn't your choice. 12^2 and 35^2 together make up 1369 or 37^2 in which B also isn't your choice. 10^2 and 24^2 together make up 676 or 26^2 in which D isn't your choice as well. The final option C makes up 7.21 when square rooted in which it is not represented by the side lengths of a right triangle.
