Utilize the input text as a context reference, choose the right relationship between 'El Abra mine' and 'copper' from the options.
Options: product/material produced, chief executive officer, founded by, operator

SANTIAGO Aug 31 (Reuters) - A Chilean union that represents copper mine workers rejected a move by Freeport-McMoRan Inc to drastically cut staff at its El Abra mine and said on Monday it was considering action.
product/material produced