How to get exposed filter dropdown option selected value in drupal hook
First of all, look up the exact filter's name. To do that open your view's builder UI and go to this exposed filter's settings page; look for the "Filter identifier" text field.

After that, you can get the filter's currently selected value in hook_form_alter(): 

function myModule_form_alter(&amp;$form, $form_state, $form_id) {
    if ($form_id == 'views_exposed_form'){
        $view = &amp;$form_state['view'];
        if ($view-&gt;name == 'your view name' &amp;&amp; $view-&gt;current_display == 'page_1') {
            var_dump($view-&gt;exposed_input['your filter identifier']);
            // OR
            var_dump($form_state['input']['your filter identifier']);
        }
    }
}