What is the relationship between 'Volvo' and 'truck' in the context of the input sentence.
Options: manufacturer, product/material produced, headquarters location, position held

Dan Kieffer of PACCAR Inc., speaking for a group of heavy-duty North American truck manufacturers including Volvo and Daimler, said, “Unnecessarily stringent engine standards will only exacerbate today’s trend of delaying new truck purchases,” and consequently keep older, not-as-clean trucks on the road.
product/material produced