In the context of the input sentence, determine the relationship between 'smelting' and 'metal'.
Options: product/material produced, distributed by, publisher, director/manager

Keller Rohrback has also handled environmental litigation involving home heating oil, contaminated drinking water, contaminated sediments, landfill leachate, metal smelting and finishing wastes, tank farms, chemical plants, gas stations, and major manufacturing concerns.
product/material produced