你已從現有的影片廣告中找出高轉換率的重要目標對象，但想要再進一步提升轉換率。 這時應該如何透過 Google 的實驗工具達成上述目標？

The correct answer is to test multiple creatives against a single high-converting audience segment. This approach allows you to isolate the impact of different ad creatives on a specific, valuable audience. By varying the creative while keeping the audience constant, you can determine which creative elements resonate most effectively and drive higher conversions within that already successful segment. Testing a single creative against all audience segments (option 1) wouldn't help optimize for a specific high-converting audience. Testing multiple creatives against two audience segments (option 3) or the same creative against two segments (option 4) introduces too many variables, making it harder to pinpoint the exact reason for performance changes and effectively optimize for the identified high-converting audience. The goal is to refine performance within a known successful group.