Evaluate the following business scenarios to determine if Meta Ads would be the most suitable primary user growth channel:
- Scenario I: A startup offering innovative, visually appealing smart home gadgets.
- Scenario II: A local plumbing service looking to expand its customer base.
- Scenario III: An online bookstore with a large inventory but low-profit margins per book.
- Scenario IV: A luxury fashion brand aiming to enhance its brand image and reach a high-income audience.
Select the scenario(s) where Meta Ads would be an effective primary user growth channel.