Dozer! I don't even know her!

As some of you know we have a bull named Dozer; give credit to Sarah for the creative name. Get it. We have a bull dozer. He has a story he has not told us. Not about the fun he has had and we all know that bulls have fun, but about how he lost his nose ring. Yes he had a nose ring, but tonight when I showed Sarah this picture she noticed he didn't anymore.
I am curious how many of you out there in blogger land know why bulls have nose rings.
A. To rattle against metal objects like bale rings or gates to tell his cows he's the bull
B. To be used as part of his bit when they are rode as bucking bulls
C. To keep from getting their noses in the wrong places, like you know where
D. To be tied up and led around like a pet
Send us your guess as a comment.