Final answer:
The League of Women Voters would most likely celebrate the passage of the Nineteenth Amendment.
Step-by-step explanation:
The news mentioned in the headline is the passage of the Nineteenth Amendment. This amendment granted women the right to vote in the United States. The organization that would most likely celebrate this news is the League of Women Voters, as they were a key advocate for women's suffrage and played a significant role in promoting the passage of the amendment.
Learn more about Advocacy for women's suffrage