Which principle is established by the 19th Amendment?

The correct answer is the one that refers to women's suffrage, which is the primary principle established by the 19th Amendment to the United States Constitution. Ratified in 1920, the 19th Amendment granted women the legal right to vote, thereby significantly advancing gender equality in the electoral process. This amendment was a pivotal achievement of the women's suffrage movement, which fought tirelessly for decades to secure voting rights for women across the country.

By enshrining women's right to vote in the Constitution, the 19th Amendment marked a transformative shift in American democracy, ensuring that women's voices would be heard in political matters and that they could participate fully in the civic life of the nation. This achievement not only affected electoral politics but also had broader implications for the status of women in society, contributing to further advancements in civil rights and gender equality.

The other options listed do not relate to the 19th Amendment: alcohol prohibition is associated with the 18th Amendment, income tax regulation pertains to the 16th Amendment, and freedom of speech is covered under the First Amendment. Each of these amendments addresses different aspects of American civil rights and governance, highlighting the unique significance of the 19th Amendment in the context of women's rights.