Analyze the relationship between 'Plug Power' and 'fuel cell' within the context of the input sentence.
Options: legal form, platform, member of, product/material produced

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.
product/material produced