Help Detective Paws complete his case notes by choosing the correct phrase.

The suspect claimed he was fast asleep during the heist, but given the trail of artisanal cheese wrappers leading straight from the vault to his bed, he ______________ a midnight snack while the diamonds went missing.

The correct answer is must have been enjoying.

We use must have been + present participle (the modal perfect continuous) to make a strong logical deduction about an ongoing action in the past based on present evidence.

"Should have been enjoying" incorrectly implies unfulfilled advice or obligation. "Can't have been enjoying" contradicts the physical evidence of the wrappers. "Might be enjoying" refers to the present moment, not the time of the heist.