Vipz,
<!DOCTYPE html>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<style type="text/css">
</style>
<script>
window.addEventListener('DOMContentLoaded', function() {
var control = document.querySelector('.form-control');
[].forEach.call(document.querySelectorAll('button'), function(item) {
item.addEventListener('click', function() {
control.selectedIndex = this.id - 1
});
});
});
</script>
</head>
<body>
<button id="1" type="button">Выбрать</button>
<button id="2" type="button">Выбрать</button>
<button id="3" type="button">Выбрать</button>
<button id="4" type="button">Выбрать</button>
<select class="form-control" name="nabor">
<option selected="selected" value="Яблоки">Яблоки</option>
<option value="Мандарины">Мандарины</option>
<option value="Апельсины">Апельсины</option>
<option value="Гранат">Гранат</option>
</select>
</body>
</html>