Answer:
Last night, 2 boys were playing baseball in front of their neighbour's house. The neighbour reported hearing glass shatter, and ran over to see what it was, but slipped on the baseball and ended up in the hospital. Back to you, Janet.
The answer is C.
The sentence is a run-on as it shows 2 different subjects, the dog. and the cat.
It helps the reader to understand the text and also helps with remembering events that happen in the story.