A grid of 40 white circles arranged horizontally on a black SVG canvas undulates vertically in a smooth, periodic wave, with each circle’s height determined by a sine function of its index and a shared time parameter. Using D3 v6, the example selects the SVG element, binds data to an array of 40 values, appends circle elements, and animates them with `d3.timer`, updating the `cy` attribute each frame. The rendering relies solely on D3’s selection and data-join methods without any external data source.