The demand was so great that they had to reprint the book immediately.

Đáp án A
Dịch nghĩa: Nhu cầu rất lớn đến nỗi họ phải in lại cuốn sách ngay lập tức.
Xét các đáp án:
A. So great was the demand that they had to reprint the book immediately. → Cấu trúc đảo ngữ: So + Adj/Adv + Auxiliary + S + V + that-clause.
B. So great the demand was that they had to reprint the book immediately. → Trong cấu trúc đảo ngữ với So ở đầu, sau adj/adv là một trợ từ, không phải một danh từ.
C. Such great was the demand that they had to reprint the book immediately. → Cấu trúc đảo ngữ: So + Adj/Adv + Auxiliary + S + V + that-clause (nếu dùng cấu trúc such ở đầu câu thì such + to be).
D. Such was the demand great that they had to reprint the book immediately. → Cấu trúc đảo ngữ: Such + to be + N + that + Clause; vì thừa “great” nên D sai