Who elects U.S. senators?

Why this is the answer

Senators are elected directly by the citizens of their state. It was not always so: the original Constitution had state legislatures choose senators, and the 17th Amendment, ratified in 1913, gave the choice to the voters. Since then a Senate election works like any other statewide election, and every voter in the state has a say. Memory hook: the people of the state elect the people who represent the state.