Which sentence is punctuated correctly?

A: The writer said, “I expect to be finished with this novel in a month.”

B: The writer said “I expect to be finished with this novel in a month.”

C: The writer said I expect to be finished with this novel in a month.

D: The writer said, ‘I expect to be finished with this novel in a month.’

The sentence punctuated correctly is:

A: The writer said, “I expect to be finished with this novel in a month.”