Read the excerpt from a folktale.

poor leo the lion, worried he would never escape the hunter’s net! then, who did he see scampering through the jungle? the same mouse he had released from his trap just a few days before. when the mouse saw his friend, the lion, he quickly nibbled through the knotted net and set him free. "you rescued me,” the mouse said. "now it’s my turn to set you free! ”

which theme can be found in this excerpt?

a/watch out for hunters’ nets in the jungle.
b/little mice have extremely sharp teeth.
c/when we others, we ourselves.
d/don’t be afraid, even when you are all alone.