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.

We will also continue to focus on last mile residential optimization by directing certain U.S. day-definite residential and rural FedEx Express shipments into the FedEx Ground network to increase efficiency and lower our cost to serve.

Answer: subsidiary