What is the relationship between Facebook and Mark Zuckerberg 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.

Facebook CEO Mark Zuckerberg has long warned that the company would be increasing expenses more quickly than revenue as it moved to grab an increasing share of users' attention around the world, especially on mobile and video.

Answer: founded_by