Choose the sentence in which the modal verb is used INCORRECTLY.

Question

Accepted Answer

Scientists warn that the rate of warming must accelerated beyond safe thresholds if we fail to act.

Answer

Scientists warn that the rate of warming might have already crossed dangerous levels.

Answer

Scientists warn that the rate of warming could accelerate beyond safe thresholds if we fail to act.

Answer

Scientists warn that the rate of warming must have accelerated beyond safe thresholds.

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