Analyze the relationship between 'Mack Trucks' and 'Truck' within the context of the input sentence.
Options: business division, product/material produced, distribution format, founded by

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