Utilize the input text as a context reference, choose the right relationship between 'Syriza' and 'Alexis Tsipras' from the options.
Options: legal form, currency, publisher, chairperson

Prime Minister Alexis Tsipras and his ruling Syriza party's major issue with bailout proposals so far has been that they effectively turn Greece into a zombie country, stumbling along the poverty line and existing solely to pay off its heavy debts.
chairperson