For the given shapes, which one of the following statements is not correct?

The correct option is One of them is not a parallelogram.

Let us analyze the shapes shown in the image below:

1. Definition of a Parallelogram:
A parallelogram is a quadrilateral with two pairs of parallel opposite sides. Rectangles, squares, and rhombuses are all special types of parallelograms.

2. Analyzing the Given Shapes:
From left to right, the four given geometric shapes are:

• First shape: A general parallelogram (opposite sides are parallel).
• Second shape: A square (all sides equal and all angles 90°). Since a square is both a rectangle and a rhombus, it is also a parallelogram.
• Third shape: A rectangle (opposite sides equal and all angles 90°), which is also a parallelogram.
• Fourth shape: A rhombus (all four sides equal), which is also a parallelogram.

3. Evaluating the Statements:
- All are parallelograms: Correct, because every shape shown satisfies the properties of a parallelogram.
- Two of them are rhombuses: Correct, because both the square and the rhombus have four equal sides.
- Two of them are rectangles: Correct, because both the square and the rectangle have four right angles.
- One of them is not a parallelogram: Incorrect (Not correct), since all four shapes are indeed parallelograms.

Therefore, the statement that is not correct is "One of them is not a parallelogram."