Here's why:
* Exclamatory sentences express strong emotion or surprise. They often start with "Oh!", "Wow!", or "Ouch!", and end with an exclamation mark (!).
Let's look at why it's not the other types:
* Declarative sentences make statements.
* Interrogative sentences ask questions.
* Imperative sentences give commands or instructions.
"Ouch that hurts" doesn't make a statement, ask a question, or give a command. It simply expresses pain.