Refer to the input text as context and select the correct relationship between 'Mack Trucks' and 'Truck' from the available options.
Options: distribution format, founded by, business division, product/material produced

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