Answer: d) An effective legal system.
Explanation:
Roman law ruled in ancient Rome since the establishment of the city (753 BCE) and up to the decline of the Western Empire (5th century CE). After that, Roman law remained in the Byzantine Empire until 1453. And even in the present, Roman law as a legal system has influenced the law in most Western civilizations, and parts of the East, and is still today the foundation for the law principles of most of Europe and derivative systems in other continents.
