public function serialize(GridQuestion $gridQuestion, array $options = [])
    {
        $serialized = [
            'penalty' => $gridQuestion->getPenalty(),
            'rows' => $gridQuestion->getRows(),
            'cols' => $gridQuestion->getColumns(),
            'sumMode' => $gridQuestion->getSumMode(),
            'border' => $gridQuestion->getGridStyle(),
            'cells' => $this->serializeCells($gridQuestion, $options),
        ];

        if (in_array(Transfer::INCLUDE_SOLUTIONS, $options)) {
            $serialized['solutions'] = $this->serializeSolutions($gridQuestion, $options);
        }

        return $serialized;
    }