The trees were breaking apart because the bark and outer layer of wood froze first, then the inner wood and sap froze. When the sap froze, it expanded and had nowhere to go, so the trees exploded.
I think the best answer is history. The story of the Trojan War is primarily an example mythology where the purpose is for history. Mythology was one means to describe the environment during the ancient times. Myths were used to re-tell historical events.
The correct answer is argumentation, or argumentative writing. It is a type of writing where the author is giving his or her arguments as to why they believe their position is the correct one. He or she is explaining why their ideas should be respected, even though they are controversial and unlike those of other people.