Understanding the Shapes
When we talk about shapes, we often describe them based on their angles and sides. Let's analyze the options given in the question:

Square
- A square has four equal sides and each angle measures 90 degrees.
- Therefore, the sides of a square meet at right angles.

Rectangle
- A rectangle also has four sides, with opposite sides being equal in length.
- Like a square, all angles in a rectangle are 90 degrees, meaning the sides meet at right angles.

Triangle
- A triangle has three sides.
- While it can have angles that are not 90 degrees, in general, triangles can have right angles as well, depending on their type (e.g. right triangle).
- However, there are also triangles that have all angles less than 90 degrees, known as acute triangles.

Circle
- A circle is a unique shape defined as the set of all points equidistant from a center point.
- It does not have sides or angles, and therefore, cannot have sides that meet at right angles.
- Since it is a continuous curve, it never forms any corners.

Conclusion
The correct answer is option 'D' (Circle) because it is the only shape listed that does not have sides or angles that can meet at right angles. All other options (square, rectangle, and triangle) involve straight sides and can have right angles.

A circle does not have sides meeting at right angles.