Deer are the only animals with bones sticking out of their heads. Some animals have horns, but horns aren't bones. They're more like fingernails....

Deer are the only animals with bones sticking out of their heads.  Some animals have horns, but horns aren't bones.  They're more like fingernails.  Deer have true bones.  Every year two new bones grow from the top of a deer's head.  At first the bones are soft and covered with skin.  Later the skin dries up.  The deer rubs off the skin.  The bones get hard.  The deer uses these horns for fighting.

The story mainly tells about---

a. what deer like to use for fighting.

b. how deer grow bones out of their heads.

c. which animals have horns on their heads.

d. why deer have fingernails