What is the relationship between 'GMC' and 'truck' in the context of the input sentence.
Options: developer, chief executive officer, product/material produced, manufacturer

GM Posts the Industry's Largest Retail Sales Increase on Double-digit Gains in Pickup and Crossover Sales Tue, Sep 1 2015 Chevrolet crossovers up for ninth consecutive month - best August ever Chevrolet truck sales up for 16th consecutive month Double-digit sales increase for GMC pickups Buick crossovers up 28 percent Cadillac SRX up 52 percent Commercial deliveries up for 22 consecutive months
product/material produced