Which sequence completes a two-chunk ASGI HTTP response correctly?

Which sequence completes a two-chunk ASGI HTTP response correctly?

1. One http.response.start, then body with more_body true, then body with more_body false
2. Two http.response.start events, one before each body
3. A body event first, then http.response.start
4. One body with more_body true and no later event