Which of the following sentences uses proper punctuation?

You don't understand, I said. "Please explain why you think that."

"You don't understand", I said. Please explain why you think that.

You don't understand, I said. Please explain why you think that.

"You don't understand," I said. "Please explain why you think that."

Question

Which of the following sentences uses proper punctuation?

 You don't understand, I said. "Please explain why you think that."

 "You don't understand", I said. Please explain why you think that.

 You don't understand, I said. Please explain why you think that.

 "You don't understand," I said. "Please explain why you think that."

anonymous · Answer

D. there is nothing wrong with it, everything is right, I'm 100% certain.