The smallest unit among the options you provided is a pixel.
- Pixel: The smallest unit of a digital image or display, representing a single point in the image.
- Wireframe: A visual representation of a 3D object, consisting of lines and vertices. It is used in 3D modeling and design and is not a physical measure.
- Primitive: In computer graphics, a primitive is a basic shape (like points, lines, or polygons) that serve as the building blocks for more complex shapes.
- Pica: A typographic unit of measure, commonly used in publishing. One pica is equal to 12 points (and approximately 1/6 of an inch).
So, in summary, the correct order from smallest to largest looks like this: pixel < primitive < pica < wireframe.