"Once upon a time there was a little girl named Goldilocks she went for a walk in the forest."  This this a Run-on Sentence. True or False?

"She came upon a house, and she became curious."   This is considered a Run-on Sentence.

She knocked and no one answered she walked right in.

She knocked, nobody answered she then walked right in.

She knocked, and no one answered, so she walked right in. 

At the table in the kitchen, there were three bowls of porridge. 