The correct option is (c) II, I, IV and III
— Napoleonic wars (early 1800s) → Treaty of Vienna (1815) → Victor Emmanuel II proclaimed King of Italy (1861) → William I proclaimed German Emperor (1871).
Memorise these four key dates: Napoleonic wars began ~1803, Treaty of Vienna 1815, Italian unification/Victor Emmanuel II 1861, German Empire/William I 1871. The passage explicitly states Vienna Treaty came after Napoleonic wars, Victor Emmanuel II was proclaimed king in 1861, and the German Empire was proclaimed on 18 January 1871.