code: function(collection, newOption, firstActivation) {
          if (newOption) {
            collection.find('li.selected').removeClass('selected');
            var option = $(newOption);
            option.addClass('selected');
            if (!multiple || !!firstActivation) {
              options.scrollTo(option);
            }
          }
        }
docs: Make option as selected and scroll to selected position
  @param {jQuery} collection  Select options jQuery element
  @param {Element} newOption  element of the new option
  @param {Boolean} firstActivation  If on first activation of select