Different ideas are as follows:
(i) Liberals believed in changing society, thought that only propertied men should have right to vote.
(ii) Radicals believed in rule of majority, supported women's right to vote.
(iii) Conservatives approved both liberals and radicals, accepted the change but believed that past has to be respected.
Or
US joined the Allies in 1917 and defeated Germany and the Central Powers.
(i) The defeat of Germany resulted in the abdication of German Emperor. This gave an opportunity for the parliamentary parties to bring a change in German politics.
(ii) A democratic constitution with a federal structure was formed by the National Assembly, which met at Weimar and the Weimar Republic came into existence.