By definition a triangle's third side must be larger than the difference of the other two sides (so in this case 10-10 = 0, so it must be larger than 0) and smaller than the sum (so 10+10 = 20 so it must be smaller than 20). Because this is not a specific type of triangle such as a right triangle, this is really the only rule that applies in this problem, so everything except E and F apply.
