This task is about reflecting the numbers you have given. So if you had 3 and -3 in the first point, the second one is -3 and 3, following 6 and 3 is reflecting 3 and 6. Finally 3 and 3 reflection is 3 and 3 :)
To enable a set of three numbers to represent three sides of a triangle, sum of smaller two numbers must be greater than the largest number. Hence, only C can represent a triangle
