Refer to the input text as context and select the correct relationship between 'Syriza' and 'Alexis Tsipras' from the available options.
Options: chairperson, developer, chief executive officer, subsidiary

Greek Prime Minister Alexis Tsipras was on Wednesday mulling whether to hold early elections after the austerity bailout split his radical left Syriza party, leaving him powerless to push further reform bills through parliament.
chairperson