Implode function error

//PHP code

<?php  $category_get = $conn->query("SELECT DISTINCT `list` FROM all_list");
while ($options = $category_get->fetch_assoc()){
if($category_fetch==implode($options)){$setval="selected";}else{$setval="";}
echo "<option value=".implode($options)." ".$setval.">".implode($options)."</option>";}
?>

//Output

<div class="col-md-6 col-sm-6 col-xs-12">
<select class="select2_single form-control">
<option value="Construction">Construction</option>
<option value="Electrical" works="">Electrical works</option>
</select>
</div>

//In Database values
ID List
1  Construction
2  Electrical works