New Post: Page still refresh in Firefox even though I'm using SPServices

Sir i have two dropdown then if I select from the first dropdown the second dropdown will be populated but the page refresh in Firefox whenever I select from the first dropdown. It's working fine in IE,Chrome and Safari.

$("#business_list").change(function(){
var btype = $(this).val();

    $("#postTo").empty().append("<option></option>");
    $().SPServices({
        operation: "GetListItems",
        async: false,
        listName: "Business Contacts",
        CAMLViewFields: "<ViewFields><FieldRef Name='Title'/></ViewFields>",
        CAMLQuery: "<Query><Where><Eq><FieldRef Name='BusinessType'/><Value Type='Text'>" + btype + "</Value></Eq></Where></Query>",
        completefunc: function (xData, Status) {
            $(xData.responseXML).SPFilterNode("z:row").each(function () {
                var title = ($(this).attr("ows_Title"));
                projListDD2(title);
            });
        }
    });

});

function projListDD2(d) {

    $("#postTo").append("<option>" + d + "</option>");

}