When did scientists discover that oysters were in danger?At the beginning of this century

* Hướng dẫn giải

Đáp án B

Theo thông tin trong bài “Until recently; the supply of wild oysters and those crudely farmed were more than enough to satisfy people's needs. But today the delectable seafood is no longer available in abundance. The problem has become so serious that some oyster beds have vanished entirely”® các nhà khoa học phát hiện rằng loài hàu đang gặp nguy hiểm ở trong đầu thế kỷ này