---- Who told you my email address? ---- I don’t remember clearly. It _______ Karen. ---- It ___ 28. ---- Who told you my email address? ---- I don’t remember clearly. It _______ Karen. ---- It _______ Karen. She doesn’t know my email address. A.may have been; can’t have been B.must have been; mustn’t have been C.may have been; must have been D.must have been; mustn’t be