What is the relationship between Plug Power and fuel cell 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.

Leading fuel cell developer, Plug Power Inc. PLUG enjoyed an upswing of as much as 14.8% on Monday to close at $2.17 per share on conjectures that big orders could be on the way from Atlanta, GA-based home improvement retailer The Home Depot, Inc. HD.

Answer: product_or_material_produced