What guaranteed women the right to vote in the united states?

a.
a supreme court decision

b.
an executive order signed by the president

c.
a law passed by the u. s. congress

d.
an amendment to the u. s. constitution

An amendment (XIX  -- 19) to the US Constitution was passed in 1920. It was a hard and long fought battle with women having to endure unimaginable horrors which bordered on torture.

It is much taken for granted today, but it was only because women fought valiantly and relentlessly in the 1800s and early 1900s. Wilson finally relented and signed the bill that was to become suffrage bill of 1920.  

Answer D