Mark the letter A, B, C, or D on your answer sheet to indicate the cor

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.    

Please meet me at the train station in ......... hour from now.

• A. A. a
• B. B. an
• C. C. the
• D. D. no article

"hour" bắt đầu bằng một nguyên âm => dùng "an"