This interactive visualization lets users explore categorical data through bar and pie charts, dynamically switching between chart types and selecting which data column to aggregate. It displays absolute frequencies for university student grades across different degree programs. The implementation uses React with D3 v5, employing `d3.scaleBand`, `d3.scaleLinear`, and `d3.scaleOrdinal` for the bar chart, and `d3.pie` with `d3.arc` for the pie chart. Both charts feature animated transitions via `transition().duration()`, hover tooltips, and interactive dropdown menus for column selection.