This example shows how to connect pairs of points with lines using D3.js version 3 within a React framework, rendering the result as SVG. It defines a dataset of three line segments, each containing two coordinate pairs, and plots them on a Cartesian grid with linear scales for the x and y axes. The code uses `d3.svg.line()` to generate the path data for each segment and applies it to SVG path elements via `.datum()` and the `d` attribute, while axis generation relies on `d3.svg.axis()`.