A bar chart displays the average marks for students aged 18–69, with each bar representing an age group's mean score. The visualization uses a vertical bar layout with percentage-based y-axis labels and animated bar entrance transitions. Built with D3 v4, the chart employs `d3.scaleBand` for x-axis positioning and `d3.scaleLinear` for the y-axis. Bars animate in sequentially using `transition().duration(400).delay(i * 50)`, while mouseover and mouseout handlers highlight bars in orange and display tooltip-like value labels. The data comes from the included `attend_data.csv` file.