A correlation matrix heatmap displays pairwise correlations among seven physical measurements of abalone (Length, Diameter, Height, and various weights) from the `abalone.data` file. Users select a subset (Male, Female, or Infant) via a dropdown menu. The visualization uses D3 v5 and the jeezy library's `arr.correlationMatrix` to compute correlations, with `scaleBand` for axes and a diverging `scaleLinear` color scale (pink to steel blue) mapping correlation values.