For the given shapes (parallelogram, square, rectangle, rhombus), which one of the following statements is not correct?

The four shapes shown - parallelogram, square, rectangle, and rhombus - are all parallelograms (quadrilaterals with two pairs of parallel sides). A square is both a rectangle and a rhombus. So all four ARE parallelograms, making 'One of them is not a parallelogram' the incorrect statement. Two of them (square and rhombus) are rhombuses, and two (square and rectangle) are rectangles.