Refer to the input text as context and select the correct relationship between 'smelting' and 'metal' from the available options.
Options: distributed by, product/material produced, director/manager, publisher

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