Utilize the input text as a context reference, choose the right relationship between 'Syriza' and 'Alexis Tsipras' from the options.
Options: distributed by, member of, chairperson, director/manager

Greek voters overwhelmingly rejected international creditors' tough bailout terms Sunday, but premier and Syriza leader Alexis Tsipras insisted the result does not mean a "rupture" with Europe despite fears it will end in a "Grexit" from the eurozone.
chairperson