What Event Finally Spurred the Granting of Suffrage to All

What event finally spurred the granting of suffrage to all American women in 1920?

A) Southern states gave the vote to women.
B) The Supreme Court ruled that it was unconstitutional to deny women the right to vote.
C) Congress passed the Nineteenth Amendment, which was subsequently ratified by two-thirds of the states.
D) Woodrow Wilson granted woman suffrage by executive order.