Hot to store sql output to array in PHP?

Here is function:

protected function get_answers_with_question_id($id){
    global $wpdb;

    $sql = "SELECT *
            FROM {$wpdb->prefix}aysquiz_answers
            WHERE question_id=" . $id;

    $answer = $wpdb->get_results($sql, 'ARRAY_A');

    return $answer;
}

Call function:

    foreach ($questions_ids as $id) {
        
    $answers2[] = $this->get_answers_with_question_id2($id);
        
    }

Actual output:

[[{"answer":"1000"}],[{"answer":"1000"}],[{"answer":"1000"}]]

I need classic array: array(key=>value,key=>value,key=>value,etc.)

source https://stackoverflow.com/questions/76547247/hot-to-store-sql-output-to-array-in-php