Every equilateral triangle is isosceles. There exist triangles that are equilateral. Choose the correct answer below. A. No triangles are equilateral. B.If a shape is isosceles, then it is a triangle. If a shape is isosceles, then it is a triangle. C.All triangles are isosceles. All triangles are isosceles. D.There exist triangles that are isosceles. There exist triangles that are isosceles