This interactive bar chart compares average cholesterol levels (in milligrams) across fast food restaurant chains, using data from a Kaggle nutrition dataset. Each bar is color-coded by company, and hovering over a bar turns it black while displaying a tooltip with the precise average value. Built with D3, the visualization uses `scaleBand` and `scaleLinear` for axes, and the `viz()` function renders the chart with responsive dimensions from `observeResize`. The tooltip and hover interactions are implemented with D3 `select` and event listeners.