function selectDataset(d) {
        let value = this.value;
        if (value == "total") {
            change(datasetTotal);
        } else if (value == "option1") {
            change(datasetOption1);
        } else if (value == "option2") {
            change(datasetOption2);
        }
    }

    function changeColor(d) {
         let value = this.value;
        if (value == "total") {
            d3.selectAll("rect")
                    .transition()
                    .duration(2000)
                    .style("fill", 'blue')
        } else if (value == "option1") {
            d3.selectAll("rect")
                    .transition()
                    .duration(2000)
                    .style("fill", 'red')
        } else if (value == "option2") {
           d3.selectAll("rect")
                    .transition()
                    .duration(2000)
                    .style("fill", 'yellow')
        }

    }

d3.selectAll("input").on("change", function(d) {
         selectDataset.call(this, d);
         changeColor.call(this, d);
        });