The correct answer is - monarchy.
The westernization of Russia came through the monarchy, as they were the ones that first accepted it, and after that enforced it on the people, very often with strict punishments if the people didn't wanted to adopt certain cultural aspects from the West.
The biggest Western cultural influence in Russia came from France. The monarchy was seeing the French culture as the best and superior to the others, thus tried to shape itself and the society in accordance to the French model. It is maybe ironical that the French influence is the biggest considering the fact that the monarchy in Russia was predominantly of German ancestry.