I am sure he did not know that...

Câu hỏi: I am sure he did not know that his brother graduated with flying colors.

A. He should not have been envious of his brother's achievement.

B. He cannot have known that his brother graduated with very high marks.

C. That his brother graduated with flying colors must have been appreciated by him.

D. He may not know that his brother is flying gradually up in a colorful balloon.