Which of the following is not a parallelogram ?

Options

A. Square
B. Rectangle
C. Rhombus
D. Trapezium

Answer

To determine which of the given shapes is not a parallelogram, we need to analyze the properties of each shape mentioned in the options: square, rectangle, rhombus, and trapezium.

### Step-by-Step Solution:

1. **Understand the Properties of Parallelograms:**
- A parallelogram is a quadrilateral with opposite sides that are parallel and equal in length. The opposite angles are also equal.

2. **Analyze Each Shape:**
- **Square:**
- All sides are equal, and opposite sides are parallel. Thus, a square is a parallelogram.
- **Rectangle:**
- Opposite sides are equal and parallel, and all angles are right angles. Therefore, a rectangle is also a parallelogram.
- **Rhombus:**
- All sides are equal, and opposite sides are parallel. Hence, a rhombus is a parallelogram as well.
- **Trapezium (Trapezoid in some regions):**
- A trapezium has only one pair of opposite sides that are parallel. The other pair of sides is not parallel.

3. **Conclusion:**
- Since a trapezium does not have both pairs of opposite sides parallel, it does not meet the criteria to be classified as a parallelogram.

Thus, the answer is that the trapezium is **not a parallelogram**.

### Final Answer:
**Trapezium is not a parallelogram.**