In the novel Where the Red Fern Grows, Billy heard the scream of a mountain lion when he was spending the night in a cave so, letter A is the correct answer. He was already sleeping when he heard a noise that resembles a woman’s scream but he was scared to death when he realized the noise is coming from a mountain lion.
He rebuilds the fire to ward of the lion and protect himself and the pups he rescued earlier that day. He cannot imagine the pups getting harmed and hurt and that made him want to protect them with all his life. He and the older dogs did not sleep the whole night in protecting the pups until the mountain lion leaves in the morning.