Answer:
Simple sentence.
Step-by-step explanation:
A simple sentence does not have commas and cannot be separated into two different sentences.
Example of a compound of sentence: Millie decided that she would eat out today, so she went to Long John's.
Simple sentence(s) version: Millie decided she'd eat out today. She went to Long John's.
Example of a simple sentence: Ajay fished on a boat.
Example of a more complex-looking simple sentence: Jayden got his name from his mother's quick thinking after his birth.