Answer:
Buck was returning to his ancient instinctual roots is the answer.
Step-by-step explanation:
the Call of the Wild is a book written by Jack London, an American writer and journalist. The question refers to the main character, Buck, which was a dog taken to Alaska after he is stolen from his home in California. The speaker considers Buck's progress as a retrogression because he was coming back to his feral instincts in order to survive in such hard conditions as a sled dog.