The statement that correctly compares the differences between Ethiopia’s and Siam’s resistance to imperialism is: Ethiopia was forced to resort to violent resistance to maintain independence, while Siam used diplomacy.
Ethiopia successfully resisted colonization in the late 19th century through military means, most notably in the Battle of Adwa in 1896 against Italian forces. On the other hand, Siam (modern-day Thailand) managed to maintain its sovereignty by skillfully engaging in diplomatic negotiations and making concessions to colonial powers, balancing their interests to avoid colonization.