Answer:
A
Step-by-step explanation:
If the square of the longest side is equal to the sum of the squares on the other 2 sides then the triangle is right.
I
longest side squared = ( )² = 74
5² + 7² = 25 + 49 = 74
Thus these sides represent a right triangle
II
longest side squared = ( )² = 106
7² + 8² = 49 + 64 = 113
These sides do not represent a right triangle
III
longest side squared = ( )² = 133
6² + 10² = 36 + 100 = 136
These sides do not represent a right triangle
The only valid sides are I → A