Welcome to your interview.
The question is on your right: Polling vs Interrupt-Driven I/O. Take a moment with it first.
Talk your thinking through with me if you like - when you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes). Discussion and graded submissions share your five interviewer interactions, so spend them well.
Explain the difference between polling and interrupt-driven I/O. When would you choose one over the other in an embedded system, and what trade-offs would you consider around CPU usage, latency, and implementation complexity?