What is the relationship between FedEx and FedEx Ground in the context of the input sentence. Choose an answer from: 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.

Last mile optimization, which is delivery of specific FedEx Express residential and rural packages by FedEx Ground has successfully launched in 26 origin markets with an additional seven markets scheduled in July.

Answer: subsidiary