Three functions to make a JSON array

Currently I'm using these three functions, that in the end produces a JSON array. I went this way so that I could fetch data from a specific table. But now it just seems bloated and poorly written, mixed with stdClass and arrays.

public static function getFraga($quiz_id = false)
{
    $database = DatabaseFactory::getFactory()->getConnection();
    $sql = "SELECT * FROM questions";
    $arg = false;
    if($quiz_id) {
        $sql .= " WHERE quiz_id = :quiz_id";
        $arg  = array(':quiz_id' => $quiz_id);
    }
    $query = $database->prepare($sql);
    if($arg) {
        $query->execute($arg);
    } else {
        $query->execute();
    }
    $data = $query->fetchAll();
    $data = json_decode(json_encode($data), true);
    $out = array();
    foreach($data as $key => $row) {
        $out[$row['id']] = $row;
    }
    return $out;
}

public static function getAnswers()
{
    $database = DatabaseFactory::getFactory()->getConnection();
    $sql = "SELECT * FROM choices";
    $query = $database->prepare($sql);
    $query->execute();
    $data = $query->fetchAll();
    $data = json_decode(json_encode($data), true);
    $out = array();
    foreach($data as $key => $row) {
        $out[$row['id']] = $row;
    }
    return $out;
}

public static function qAndA($quiz_id = false)
{
    $questions = Self::getFraga($quiz_id);
    $answers = Self::getAnswers();
    $combined  = array();
    foreach($answers as $answer) {
        if(!isset($questions[$answer['question_id']])) continue;
        $q_key = 'question-'.$answer['question_id'];
        if(!isset($combined[$q_key])) {
            $combined[$q_key] = $questions[$answer['question_id']];
        }
        $combined[$q_key]['answer'][$answer['id']] = $answer;
    }
    return $combined;
}

And I call the qAndA() to get this result, with json_encode():

{
  "question": {
    "question-5": {
      "id": "5",
      "content": "Har jag laddad upp en bild?",
      "source": "99",
      "image_url": "156ebc02fd6281_kljqpiohfngme.jpeg",
      "lastmodified": "2016-03-18 09:45:35",
      "quiz_id": "1",
      "answer": {
        "17": {
          "id": "17",
          "content": "Nej",
          "correct": "1",
          "question_id": "5"
        },
        "18": {
          "id": "18",
          "content": "ja",
          "correct": "0",
          "question_id": "5"
        },
        "19": {
          "id": "19",
          "content": "kanske",
          "correct": "0",
          "question_id": "5"
        },
        "20": {
          "id": "20",
          "content": "vet inte",
          "correct": "0",
          "question_id": "5"
        }
      }
    }
  }
}

Narrow it down to one function? Other improvements?