The statement that correctly compares differences between Ethiopia's and Siam's resistance to imperialism is:
C: Ethiopia was forced to resort to violent resistance to maintain independence while Siam used diplomacy.
Ethiopia successfully resisted Italian colonization through armed conflict, notably winning the Battle of Adwa in 1896. In contrast, Siam (modern-day Thailand) skillfully used diplomatic negotiations and modernization strategies to maintain its sovereignty and avoid colonization by European powers.