What is the relationship between 'Syriza' and 'Alexis Tsipras' in the context of the input sentence.
Options: legal form, chairperson, headquarters location, currency

While the result is a victory for Prime Minister Alexis Tsipras in that he managed to convince parliament to back him on the bailout, he did suffer a major rebellion from Syriza MPs for the second time in a week -- prompting analysts to predict he may be forced to call early elections.
chairperson