Take context from the input text and decide on the accurate relationship between 'Escondida mine' and 'Copper' from the options provided.
Options: chairperson, product/material produced, manufacturer, 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