Answer:
C) Personification
Step-by-step explanation:
Personification refers toa figure of speech that characterizes for giving a thing, and idea, or an animal human attributes. In other words, inanimate objects are described in such a way we feel they are able to act like human beings.
In this case the author is refering to some graves (excavations for burial of bodies), this graves "yawned" and "yielded up", suggesting to the reader that they are alive. In reality the author means they are open and the people can sometimes look inside them, the open space resembles a mouth.