Must be true. The politicians referred to here are known to be involved in a serious scandal. So they must be censured by their colleagues.

Could be false. This confuses sufficient with necessary. Denying the sufficient condition (“known to be involved in serious scandal”) doesn’t tell us whether the necessary condition (”not reelected”) is also denied. Even politicians who aren’t known to be involved in serious scandals can still fail to be reelected.

Could be false. This says that if a politician is censured, she must be known to be involved in a serious scandal. This swaps sufficiency for necessity. “Censured by colleagues” isn’t sufficient for “known to be involved in serious scandal.” As far as we know, politicians can be censured even without the fuss of a scandal.

Could be false. Nothing in the stimulus suggests that they benefited. The only things we know about the consequences of the conspiracy are that it turned into a serious scandal and it became known, which satisfies the sufficient condition and so triggers two necessary outcomes, neither of which sounds very beneficial.

Could be false. This is about politicians involved in unknown scandalous conspiracies. But we only know about politicians involved in known scandalous conspiracies. It’s possible that every time a politician is involved in a scandalous conspiracy, it becomes known.