Refer to the passage. Coming to solve it, we are of opinion that, by a consideration of the text of the suffrage amendment insofar as it deals with the literacy test, and to the extent that it creates the standard based upon conditions existing on January 1, 1866, the case is taken out of the general rule and brought under the first of the exceptions stated. We say this because, in our opinion, the very language of the suffrage amendment expresses, not by implication nor by forms of classification nor by the order in which they are made, but by direct and positive language, the command that the persons embraced in the 1866 standard should not be under any conditions subjected to the literacy test.

–Excerpt from the US Supreme Court’s opinion in Guinn and Beal v. United States (1915)

How did Guinn and Beal v. United States (1915) affect voters’ rights?

It expanded 15th Amendment rights by giving all citizens the right to vote.
It limited 15th Amendment rights by supporting the use of literacy tests for voters.
It clarified 15th Amendment rights by ending a state restriction on minority voting rights.
It restricted 15th Amendment rights by allowing state regulation regarding voter requirements.