How can $4$ points in the plane be vertices of $3$ different quadrilaterals?

Question

Four points on the plane are vertices of three different quadrilaterals. How can this happen?

The problem is taken from "Kiselev's Geometry - Book I : Planimetry"

At first, I thought it could be like this :

But, the way diagonals are defined in the book:

Makes me think that the 3 figures I drew, are the same quadrilateral.

How do you think four points on the plane can be vertices of three different quadrilaterals

Answer 1

One point (say D) is inside the triangle formed by the other three (ABC). Then the possible quadrilaterals are ABCD, ABDC or ADBC.

Answer 2

Is this what you mean by three different quadrilaterals?