You Have Just Been Put on Administrative Leave for Screaming

You have just been put on administrative leave for screaming at and hitting a teen with a nightstick who was loitering and skateboarding in a public area because he disobeyed your order to cease and desist. Until you see the video of yourself on YouTube, secretly recorded by a third party, you didn't realize how angry you had become after being disrespected and disobeyed by the teen.
-When you took this teen into custody for loitering and skateboarding in a public area, he wanted to call his mom from the squad car. The teen tells his mom that he was wrong and he was arrested. You now have evidence that you did your job and that the teen violated the ordinance against loitering and skateboarding. Why can't you use this statement against him

A) He is a minor.
B) You didn't Mirandize him.
C) You don't have a second officer as a witness.
D) You were subsequently put on administrative leave.