Final answer:
In the book 'Shiloh,' Marty builds Shiloh's pen using chicken wire. It signifies his commitment to protecting the dog from harm.
Step-by-step explanation:
In the novel Shiloh by Phyllis Reynolds Naylor, Marty constructed Shiloh's pen using C) Chicken wire. This makeshift enclosure was built to keep the dog, Shiloh, safe after Marty found him and wanted to protect him from his abusive previous owner. Marty's dedication to Shiloh's safety highlights a central theme of the book, where a young boy goes to great lengths to care for and shield an animal he loves.