In the context of the input sentence, determine the relationship between 'Codelco' and 'copper'.
Options: original broadcaster, position held, product/material produced, employer

Tell me if this is incorrect, that there were negotiations going on with Codelco about maybe making some changes to the long-term contract that you have with them in respect of how the royalty is calculated to maybe give you some better predictability of what happens under highly volatile copper prices.
product/material produced