Which statement is true about the line segments below

The answer is C.
It cannot form a triangle because the length of the two shortest sides is less than that of the longest side.

This means that even if the lengths of the shortest legs lay parallel to the base line, the lines can never meet to form a closed figure because they are too short.

If the diameter is 8 than the radius is 4 because 2r or 2*radius equals the diameter. 4*2=8. 8/2=4.