The statement that accurately describes a difference between the political systems of Australia and New Zealand is:
In Australia, citizens are required by law to vote in elections; in New Zealand, voting is not required.
Australia has compulsory voting laws, while New Zealand does not require its citizens to vote.
Additionally, the other options contain inaccuracies or don't appropriately capture the differences between the political systems of the two countries. For example, both Australia and New Zealand are constitutional monarchies, and Australia has a written constitution, while New Zealand has an unwritten constitution based on statutes and conventions.