Refer to the input text as context and select the correct relationship between 'Escondida mine' and 'Copper' from the available options.
Options: manufacturer, chairperson, product/material produced, distributed by

Copper is selling for around $2.47 a pound, not far off a six-year low, while BHP's output will also fall next year due to lower grades at its Escondida mine in Chile.
product/material produced