<div class="class-drop">
    <select name="batch_sel" >
      <option value="all" <?php if($_GET['batch_sel'] == 'all'){echo 'selected'; } ?> >All </option>
      <?php
       $terms = get_terms( array(
            'taxonomy' => 'result-year',
            'hide_empty' => false,  ) );
       $batch_slugs = wp_list_pluck( $terms, 'slug' );
     foreach($terms as $term):
     ?>

      <option value="<?= $term->slug ?>" <?php if($term->slug == $_GET['batch_sel']) { echo 'selected';} ?>> <?= $term->name ?> </option>
    <?php endforeach ?>

    </select>
</div>