Select all that apply $[$point deduction on every wrong selection, partial point on every correct selection$]$: What is a double spending attack? In the ScroogeCoin project, how to detect double spending? A$.$ In the ScroogeCoin project, we check the outputs of a transaction for coin IDs. If the coins already existed before, it$$s a double spending. B$.$ A double spending attack is creating a copy of an existing coin. C In the ScroogeCoin project, we check the inputs of a transaction for coin IDs. If the coins already consumed before, it$$s a double spending. D$.$ A double spending attack is spending the same coin twice.