What is the relationship between 'Syriza' and 'Alexis Tsipras' in the context of the input sentence.
Options: industry, stock exchange, parent organization, chairperson

ATHENS, Sept 20 The leftist Syriza party of Alexis Tsipras has won 35.54 percent of the vote in Sunday's Greek national election based on 50 percent of votes counted, the Interior Ministry said on its website.
chairperson