Utilize the input text as a context reference, choose the right relationship between Express Scripts and Cigna 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.

Express Scripts serves more than 3,000 clients covering 70 million lives, including approximately 9 million lives managed by Cigna HealthCare.

Answer: parent_organization