What change, if any, should be made in sentence 25?

(24) "This sort of thing hasn't been done before, "Downer later commented.
(25)"But now," he added, "It seems te most natural thing in the world."

Select one:
A) change world to World
B) change It to it
C) no change should be made in sentence 25.
D) change the comma after added to a period