Try this :
$('select[name^="salesrep"] option[value="Bruce Jones"]').attr("selected","selected");
Just replace option[value="Bruce Jones"]
by option[value=result[0]]
And before selecting a new option, you might want to “unselect” the previous :
$('select[name^="salesrep"] option:selected').attr("selected",null);
You may want to read this too : jQuery get specific option tag text
Edit: Using jQuery Mobile, this link may provide a good solution : jquery mobile – set select/option values
Reference Link – https://stackoverflow.com/questions/17856523/how-to-set-the-selected-option-of-a-select-dropdown-list-with-jquery