Your question is Handling Unresponsive Stakeholders. 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).
What would you do in a situation where you needed something and you were reaching out and couldn't get an answer? Explain how you would determine whether to follow up, change your communication approach, find an alternative source, or escalate. Address how you would protect the deadline and maintain a constructive relationship.