The answer is a straight line. All the interior angles in a triangle add up to 180 degrees. An obtuse angle is any angle over 90 degrees and a right angle is only 90 degrees, so those two options would not work. A circle on the other hand measures up to 360 degrees. The only option left is a straight line because in order for a line to be considered straight it has to be 180 degrees. Hope this helped :))
