What is the relationship between things and app store 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.

I think we're on the verge of seeing some big things from Microsoft, now it just needs to work on further developing its app store in the smartphone market and hitting some home runs on the innovation front that really distinguishes its products from Apple's.

Answer: distributed_by