Take context from the input text and decide on the accurate relationship between 'Syriza' and 'Alexis Tsipras' from the options provided.
Options: chief executive officer, director/manager, chairperson, creator

Greek Prime Minister Alexis Tsipras faced down a revolt by rebels in his leftists Syriza party to win parliament's backing for a second package of reforms required to start talks on a financial rescue deal.
chairperson