A. A perfect storm: This idiom refers to II. The worst possible situation or a disastrous situation created by a powerful concurrence of factors.

B. Beyond question: This means I. Undoubtedly or completely certain/definite.

C. When it rains, it pours: This idiom signifies that IV. Everything going wrong at once or when one bad thing happens, a lot of other bad things also happen.

D. Ins and Outs: This refers to III. The full details or the detailed facts about something.