What is the relationship between restrictions and music streaming 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.

Amazon Music UK head Paul Firth said: "Choice is something we don’t see at play that much in the music streaming market, so if you are a music streaming customer you can either pay £120 a year, or you can be subject to interruptions from ads or other listening restrictions through one of the free services."

Answer: distribution_format