Refer to the input text as context and select the correct relationship between 'Walgreens' and 'Walgreens Boots Alliance' from the available options.
Options: business division, parent organization, currency, stock exchange

Walgreen is part of Walgreens Boots Alliance Inc, and this year sold a majority stake in Trinity's parent Walgreens Infusion Services to private equity firm Madison Dearborn Partners.
parent organization