He said: “I’m sorry I didn’t reply to the letter.” A. He apologized for not to reply to the letter. B. He apologized for not to replying to the letter. C. He apologized for didn’t reply to19/147He said: “I’m sorry I didn’t reply to the letter.”He apologized for not to reply to the letter.He apologized for not to replying to the letter.He apologized for didn’t reply to the letter.He apologized for not replying to the letter.Giải thíchChọn D