Refer to the input text as context and select the correct relationship between 'Syriza' and 'Alexis Tsipras' from the available options.
Options: distributed by, owner of, industry, chairperson

Greek PM Tsipras under pressure over covert Syriza drachma plan reports 34 minutes ago Greek Prime Minister Alexis Tsipras in Athens, Greece July 24, 2015.
chairperson