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

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

Step 1: Understand the definition of a parallelogram
A parallelogram is a four-sided plane figure (quadrilateral) with two pairs of parallel opposite sides. Special types of parallelograms include:

• Rectangle: A parallelogram with four right angles.
• Rhombus: A parallelogram with four equal sides.
• Square: A parallelogram with four equal sides and four right angles (combining properties of both rectangles and rhombuses).

Step 2: Analyze each statement

• Statement 1: "All are parallelograms."
Since rectangles, rhombuses, and squares all satisfy the fundamental definition of having opposite sides parallel, they are all parallelograms. Therefore, this statement is correct.

• Statement 2: "One of them is not a parallelogram."
As established, all given standard geometric shapes (rectangles, rhombuses, squares) are parallelograms. Claiming that one of them is not a parallelogram is false. Hence, this statement is not correct.

• Statement 3: "Two of them are rhombuses." and Statement 4: "Two of them are rectangles."
In standard classification of geometric quadrilaterals, a square can be classified as both a rectangle and a rhombus. Thus, having multiple shapes fitting these specific definitions is correct.

Conclusion:
The statement that is not correct is "One of them is not a parallelogram."