def parse_question_update_sync_agent_data(json):
    """
    Parse the incoming statement for a sync agent event concerning a question update.

    :param json: A statement concerning a question update.
    :type json: dict(str, NoneType)
    :return: A dictionary containing a course id, quiz id and all question information.
    :rtype: dict(str, str)
    """
    statement = json['statement']
    questions_info = statement['context']['extensions']['http://activitystrea.ms/schema/1.0/question']
    course_id = statement['context']['contextActivities']['grouping'][1]['id'].split("=")[-1]
    quiz_id = statement['object']['id'].split("=")[-1]
    question_update_data = {
        'course_id': course_id,
        'quiz_id': quiz_id,
        'questions': questions_info
    }
    return question_update_data