Javier, the owner of Javier's Tacos, has noticed that residents of his town are flocking to a new taco truck in increasing numbers. After doing some research, Javier learns that consumers enjoy the food truck because almost all the taco ingredients are locally sourced. Javier decides to add locally sourced ingredients to his menu. This is an example of ______.
A. substitution
B. direct imitation
C. resource immobility
D. a value chain