Mark the letter A, B, C, or D on...

Câu hỏi: Mark the letter A, B, C, or D on your answer sheet to indicate the most suitable response to complete each of the following exchanges.
Many of the important products obtained from trees, one of the most important is wood pulp, which is used in paper-making.

A. Many of the

B. obtained

C. the most

D. paper-making