Utilize the input text as a context reference, choose the right relationship between Pebble Mine and copper from the options. Options: 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.

The community was plastered with signs like "Mines and fish don't co-exist" protesting against the Pebble Mine copper and gold project proposed by Northern Dynasty Minerals Ltd.

Answer: product_or_material_produced