Answer: The correct option is (C) a right triangle.
Step-by-step explanation: The given co-ordinates of a polygon are A(2, 1), B(7, 1), C(2, 4).
We are to select the correct type of the polygon.
Since we have the co-ordinates of the three points A, B and C, so the polygon will surely be a triangle.
Now, the lengths of the three sides AB, BC and CA of ΔABC can be calculated using distance formula as follows :

We have

This implies that

which is the Pythagorean triple. Hence, triangle ABC is a right-angled triangle.
Thus, (C) is the correct option.