Final answer:
US Senators opposed the Treaty of Versailles mainly due to the fear that Article X would commit the US to international disputes and endanger Congressional war powers, leading to the rejection of US membership in the League of Nations.
Step-by-step explanation:
The greatest resistance to the ratification of the Treaty of Versailles among US Senators was due to provisions that could draw the United States into future international conflicts, specifically through the United States' involvement in the League of Nations. This is reflected in option (c) of the original question. The Senate was especially concerned about Article X, which they feared might commit American forces to international disputes without Congressional approval, infringing on the Senate's constitutional power to declare war. Additionally, many senators were isolationists who preferred to avoid entanglements in European politics and were wary of how Britain and France might dominate the League. Ultimately, these concerns led to the United States not joining the League of Nations, weakening its international authority and significance.