The writer said, “I expect to be finished with this novel in a month.”
This option is punctuated correctly. A dialog tag at the beginning of the sentence is followed by a comma to separate the dialogue tag from the dialogue. The dialogue tag includes who is speaking and the verb which indicates that the person is speaking. The words the character or person speaks should be surrounded by double quotation marks. They must begin right before the first word of dialogue and end after the punctuation that ends the dialogue.