Answer :
It would be through. Threw is the past of throw. Through means that it goes into something,
It is through.
Threw: If it was threw then the sentence would mean: The football went flying and it would throw the window. Or something like that.
Through: If it was though the sentence would mean: The football went flying out the window.
If you use common sense, through not threw is the answer.
Threw: If it was threw then the sentence would mean: The football went flying and it would throw the window. Or something like that.
Through: If it was though the sentence would mean: The football went flying out the window.
If you use common sense, through not threw is the answer.