D3 Transitions
Six colored circles with varying radii float on a light green background. D3 transitions animate the circles growing from zero radius to their full size, with each circle entering the scene sequentially. The code uses D3's `select`, `transition`, and `easeLinear` APIs to manage enter, update, and exit selections on SVG circles. An initial transition quickly scales each circle to its target radius, while subsequent updates reposition them smoothly. Data is hardcoded as an array of circle objects with explicit x, y, and radius values.