The correct answer is 'sexual reproduction'.
I believe it's A. the Princess in "The Last of the Dragons" due to the princess giving herself to the dragon hope this helps :)
Because it shows that even the small parts of a situation are important and make up the big picture. Just like how everything is made up of tiny little cells. Without them, we wouldn't be here. So "Even the pigs joined in a critical moment" means that even the pigs are important in a critical moment.