Given that the following statement is true
"If a shape is a polygon, then it is a closed figure."
Which of the following statements must also be true?
A. If a shape is a closed figure, then it is a polygon.
B. If a shape is not a polygon, then it is not a closed figure
C. If a shape is not a closed figure, then it is not a polygon
D. If the shape is not a polygon, then it is a closed figure.