Take context from the input text and decide on the accurate relationship between 'Syriza' and 'Alexis Tsipras' from the options provided.
Options: chairperson, currency, headquarters location, owned by

Prime Minister Alexis Tsipras resigned last week after his acceptance of an 86 billion euro ($96 billion) rescue package for Greece's stricken economy triggered a major rebellion within his radical left Syriza party.
chairperson