Read the following passage and mark the lett...

Câu hỏi: Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 30 to 34.

A. A new kind of currency in the virtual world

B. A way of doing business in the virtual world

C. An alternative to bitcoins created by Nakamoto

D. The future of bitcoins in the real world.