// Select by value
$('select[name="options"]').find('option[value="3"]').attr("selected",true);
// Select by text
//$('select[name="options"]').find('option:contains("Third")').attr("selected",true);
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<html>
<body>
<select name="options">
<option value="1">First</option>
<option value="2">Second</option>
<option value="3">Third</option>
</select>
</body>
</html>