Take context from the input text and decide on the accurate relationship between 'GMC' and 'truck' from the options provided.
Options: headquarters location, product/material produced, stock exchange, location of formation

The ongoing success of the Chevrolet Silverado and GMC Sierra helped drive the ATP increase; full-size pickup truck ATPs were up $230 month over month and more than $1,000 year over year.
product/material produced