Hovering over a fruit circle highlights it in light blue while showing its selection state. The example demonstrates a unidirectional data flow pattern, where mouse events trigger a state change that re-renders the SVG. Using d3.v5's data join, circles transition their radius and position over one second with `transition().duration(1000)`. The `fruitBowl` module applies ordinal color and radius scales to map apple and lemon types to distinct visual properties, while `setSelectedFruit` updates the selected state on mouseover and mouseout.