This scatterplot shows the relationship between bill length and flipper length for penguins, using only rows with complete data for both measurements. The code filters missing values from the Palmer Penguins dataset via `isNaN` checks before passing the cleaned data to the visualization. Rendered with D3’s `scaleLinear`, `axisLeft`, and `selectAll().join()`, the chart includes labeled axes, a gray inner rectangle, and semi-transparent circles whose opacity and radius are controlled by the `circleOpacity` and `circleRadius` parameters.