6 points lie on the circumference of a ellipse . what is the positive difference between the number of triangles and the number of quadrilaterals that can be created by connecting these points ?
Choices:	A) 4	B) 6	C) 5	D) 15	E) 20

Rationale: number of triangles can be formed out of 6 points = 6 c 3 = 20 number of quadrilaterals can be formed out of 6 points = 6 c 4 = 15 20 - 15 = 5 . answer = c
Answer: C