Final answer:
The solution to the non-cohesive selection of U.S. senators before 1913 was the passing of the 17th amendment, which introduced direct election of senators.
Step-by-step explanation:
Before 1913, the selection of U.S. senators was not cohesive, with each state having different methods to appoint their senators. The solution to this was the passing of the 17th amendment by the Congress. This amendment, ratified in 1913, provided for the direct election of senators by the people of each state. Before this, senators were chosen by state legislatures.
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