Which of the following shapes has 4 sides?

The correct answer is a quadrilateral because a quadrilateral is defined specifically as a polygon with four sides. This means it can take various forms, such as squares, rectangles, trapezoids, and rhombuses, all of which have four sides.

In contrast, a hexagon is a shape with six sides, an octagon has eight sides, and a triangle has three sides. Therefore, the only shape among the given options that fits the criterion of having precisely four sides is the quadrilateral.