Utilize the input text as a context reference, choose the right relationship between Worldpay and Advent International from the options. Options: product/material produced, manufacturer, distributed by, industry, position held, original broadcaster, owned by, founded by, distribution format, headquarters location, stock exchange, currency, parent organization, chief executive officer, director/manager, owner of, operator, member of, employer, chairperson, platform, subsidiary, legal form, publisher, developer, brand, business division, location of formation, creator.

Advent International and Bain bought Worldpay from Royal Bank of Scotland in 2010 for about £2 billion.

Answer: parent_organization