What is the relationship between 'MasterCard' and 'purchase' in the context of the input sentence.
Options: developer, location of formation, chairperson, headquarters location

“Accepted in over 210 countries, wherever MasterCard is accepted, the credit cards are by far the fastest way to earn Miles with a ticket purchase to fly on SAA or make qualified merchant purchases,” said Samuel Ashitey Adjei, MD of Ecobank Ghana.
headquarters location