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

Left-wing Syriza party leader Alexis Tsipras speaks to his supporters at Syriza's partyâ€™s main electoral center in Athens, Sunday, Sept. 20, 2015.
chairperson