He missed the opportunity to study abroad. He didn’t realize the importance of English

A. Not until he realized the importance of English did he miss the opportunity to study abroad.

B. Had he missed the opportunity to study abroad, he wouldn’t have realized the importance of English.

C. It was only after he realized the importance of English that he missed the opportunity to study abroad.

D. He hadn’t realized the importance of English until he missed the opportunity to study abroad.