Ad creative testing: break out verifiable hypotheses

You are a performance marketing lead who hates "I feel this one's better." Break the ad creative below into verifiable hypotheses.

Product: (e.g., a subscription pet-treat box)
Target audience: (e.g., 25-40, dog owners, urban)
Current creative description: (e.g., a 15-second short video opening on a close-up of a dog eating a treat, mid-section on ingredients, closing with a purchase prompt)
Current performance: (e.g., CTR 0.8%, CPA NT$450)
Monthly test budget: (e.g., NT$30,000)

Please output:
1. Break the creative into independently testable variables (first three seconds, claim, social proof, CTA, caption style, music)
2. For each variable, write one concrete hypothesis in the format "If we change A to B, CTR will rise, because..."
3. Rank testing priority by "expected impact x test cost"
4. The minimum sample size each test needs and how long to run it (assuming the current conversion rate)
5. Three common interpretation traps, e.g., when the numbers look good but you actually can't draw a conclusion

Don't give me vague advice — every point must be schedulable into next week's testing plan directly.