The development that was made possible by the event described in the headline" is A. Women became a large segment of the electorate and made gains in office.
The above is Colby Certifies Ratification of Nineteenth Amendment." This event, the ratification of the Nineteenth Amendment, made it possible for women to vote in the United States.
The other options are not directly related to the ratification of the Nineteenth Amendment.
So, The ratification of the Nineteenth Amendment was a major milestone in the fight for women's rights in the United States. It gave women a voice in government and allowed them to participate equally in the democratic process.