Explain the holy alliance and clemens von mettenich

The hole alliance was a coalition created by the monarchist great powers of Russia, Austria and Prussia. It was created after the ultimate defeat of Napoleon at the behest of Tsar Alexander I of Russia and signed in Paris on 26 September 1815.[1] The intention of the alliance was to restrain liberalism and secularism in Europe in the wake of the devastating French Revolutionary Wars, and the alliance nominally succeeded in this until the Crimean War (1853–1856). Klemens Metternich was an Austrian diplomat who was at the center of European affairs for four decades as the Austrian Empire's foreign minister from 1809 and Chancellor from 1821 until the liberal Revolutions of 1848 forced his resignation.

Ithink the answer should be a.