Final answer:
The Treaty of Versailles is the historical evidence that required League of Nations members to defend each other, with Article X mandating collective defense. The United Nations was later formed to create a stronger global organization, addressing the weakness of the League of Nations. so, option a is the correct answer.
Step-by-step explanation:
Historical Evidence of League of Nations Collective Security
The historical evidence to support the point of view that required all League of Nations members to come to the aid of any member state under attack is the Treaty of Versailles. Article X of the League of Nations covenant, which was agreed upon during the negotiation of the Treaty of Versailles, stated that all member nations would agree to defend all other member nations against military threats. This agreement was a form of collective security, ensuring that each nation was equal in terms of military response because no member could use its military to overpower another. Unfortunately, while this provision was intended to deter aggression and promote peace, the lack of real enforcement mechanisms and the requirement for unanimous decisions in the League made it ineffective, as seen with the outbreak of World War II.
The creation of the United Nations post-World War II was in response to the recognition that a stronger global organization was necessary, given the failure of the League to prevent another global conflict. The United Nations sought to address the issues faced by the League by allowing actions to be taken with majority votes, rather than requiring unanimity.