Highlight elliptical arc drawn using D3.js on Mouseover and display tooltip

How do I highlight an elliptical arc drawn, on mouseover and display tooltip on the same using d3.js?
Solution
<!DOCTYPE html>
<meta charset="utf-8">
<html>
<head>
    <style>
        body { font: 10px sans-serif; }

        .d3-tip {
            background: rgba(0, 0, 0, 0.8);
            border-radius: 2px;
            color: #fff;
            font-weight: bold;
            line-height: 1;
            padding: 12px;
        }
    </style>
</head>
<body>
<script src="http://d3js.org/d3.v3.min.js"></script>
<script src="http://labratrevenge.com/d3-tip/javascripts/d3.tip.v0.6.3.js"></script>
<script>

    var w = window.innerWidth,
        h = window.innerHeight,
        margin = { top: 40, right: 20, bottom: 20, left: 40 };

    var svg = d3.select("body").append("svg").attr({
        width: w,
        height: h
    });

    var dataset = [
        { toolTip: "one", d: "M 50 200 a 100 50 0 1 1 250 50" },
        { toolTip: "two", d: "M 400 100 a 100 50 30 1 1 250 50" },
        { toolTip: "three", d: "M 400 300 a 100 50 45 1 1 250 50" },
        { toolTip: "four", d: "M 750 200 a 100 50 135 1 1 250 50" }
    ];

    var tip = d3.tip()
        .attr('class', 'd3-tip')
        .offset([-10, 0])
        .html(function(d) {
            return "<strong>Elipse:</strong> <span style='color:red'>" + d.toolTip + "</span>";
        });

    svg.selectAll("g")
        .data(dataset)
        .enter()
        .append("g")
        .attr("stroke-width", 3)
        .attr("stroke", "black")
        .attr("fill", "none")
        .on('mouseover', tip.show)
        .on('mouseout', tip.hide)
        .append("path")
        .attr("d", function(d) { return d.d })
        .on('mouseover', highLight)
        .on('mouseout', unHighLight);

        svg.call(tip);

    function highLight(){
       var foo = d3.select(this);
       foo.attr("stroke","red");
   }

    function unHighLight(){
        var foo = d3.select(this);
        foo.attr("stroke","black");
    }

</script>
</body>
</html>
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