Article: Little Tom down the street calls our dog "The keep dog".Zip is a sheep dog. But when Tom tries to say" Seep", it comes out "keep". And in a way Tom is right. Zip is always bringing things home for us to keep! I'll tell you about some of them. Zip's first present was a shoe. It was made of green silk. We didn't know how Zip found the shoe. But after a moment Mary, my big sister, told me the shoe had a strange smell. I nodded and held my nose. "What do you think it is?" "It smells like something for cleaning. I think someone tried to clean a spot   off the shoe. Then he put it at the door to dry." "Along came Zip. And good-bye shoe!" I said."We should take it back." "We can't ".said my sistter. "Maybe little Tom is right," Mary said. "Maybe Zip is a keep dog!" 
 Question: The writer and Mary didn't know  _  . 
 Options: (A) what Zip's first present was (B) how Zip carried its first present home (C) who owned Zip's first present (D) what Zip's first present was made of
C