In the context of the input sentence, determine the relationship between 'Volvo' and 'Truck'.
Options: owner of, founded by, product/material produced, brand

In what was then the largest environmental enforcement case in U.S. history, companies including industry leaders Caterpillar Inc., Cummins Engine Co., Mack Trucks and Volvo Truck Corp. agreed to pay $83.4 million in fines and reprogram the computers.
product/material produced