I mean it's not a completely wrong answer. It's just ambiguous that by adding the red herring of throwing the cigarette out, this creates ambiguity as to what "process" he is repeating on each floor. Is he opening windows and throwing out a cigarette, or just throwing out a cigarette regardless of the windows open or not?
One year back but ........ who cares if the man had commited suicide then the window that he jumped from should have been left open but all the windows facing the dead bodies are closed , so someone closed it from behind after the mans death