Answer:
C. If a polygon is not called a quadrilateral, then it does not have four sides.
Step-by-step explanation:
If P ⇒ Q is a statement, then the contra positive of this statement is:
not Q ⇒ not P.
A statement and its contra positive are equivalent.
The given statement is :
"If a polygon has four sides, then it is called a quadrilateral."
The contra positive of the above is:
"If a polygon is not called a quadrilateral, then it does not have four sides" which is given in (C).
Hence, the correct option is (C).