Your question is Pick One Idea and A/B Test. 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).
Select one method from your prioritized list and design an A/B test for it.
Asked in the Technical Phone Screen stage. Growth experiment design. Keep your answer focused on hypothesis, metrics, sample size, randomization, and analysis plan.