Your question is Define Campaign North Star Metric. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
You are planning how to measure a marketing campaign and want one clear success metric that reflects real business value. You also need supporting KPIs that help the team read performance early and diagnose what is working across the funnel.
How would you define the right north star metric and supporting KPIs for a marketing campaign?