What is the relationship between 'MasterCard' and 'purchase' in the context of the input sentence.
Options: headquarters location, founded by, member of, operator

Samuel Ashitey said the MasterCard network in over 220 million shops and businesses in over 210 countries, the SAA Voyager credit card is by far the fastest way to earn miles with a ticket purchase to fly on South Africa Airways or make qualified merchant purchase.
headquarters location