Explanation:

Symmetry is a concept that refers to the balance and equality of a shape or object. A shape is symmetrical if it can be divided into two identical halves that are mirror images of each other.

Triangle:
A triangle is a polygon with three sides. It does not have symmetry because it cannot be divided into two identical halves.

Rectangle:
A rectangle is a quadrilateral with four right angles. It also does not have symmetry because it cannot be divided into two identical halves.

Circle:
A circle is a shape with all points equidistant from its center. It is symmetrical because it can be divided into two identical halves that are mirror images of each other. Any line passing through the center of a circle will divide it into two equal halves.

Square:
A square is a quadrilateral with four equal sides and four right angles. It is the only shape among the options given that is symmetrical. A square can be divided into two identical halves by a line passing through its center. Each half will be a mirror image of the other.

Conclusion:
Among the given options, the only shape that is symmetrical is the square. It can be divided into two identical halves that are mirror images of each other. The triangle, rectangle, and circle do not have this property and, therefore, are not symmetrical.