Dropdown list show only one letter

[Tje123]

in my back office controller renderForm i have drop down list to load week days.but it showing only first letter of the day.

 

public function renderForm() {

$days=["Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"];

    'input' => [

                    [
                      'type' => 'select',
                        'lang' => true,
                        'required' => true,
                        'label' => $this->l('WeekDay'),
                        'name' => 'weekday',
                        'options' => [
                          'query' => $days,

                        ],

                    ],
         ]
    }

[NemoPS]

It's because you set lang to true