Answer:
either improve or catapult. I think it's improve.
Explanation:
simple sentence- Carrie whistled for Sassy, her cocker spaniel. Sassy came bounding down the stairs.
compound sentence- Carrie whistled for Sassy, her cocker spaniel, and Sassy came bounding down the stairs.
'their' because the sentences says one of the speakers. it doesn't clarify if the speaker is a boy or girl.
