Fill in the gap with the correct form of the word: "Alexander II was also known as the Tsar ...". Liberator Liberation

The correct answer is "Liberator". The sentence should read: "Alexander II was also known as the Tsar Liberator." This is because "Liberator" is the correct form of the word "liberation" to use as an adjective to describe Alexander II, who was known for his liberal reforms and emancipation of the serfs in Russia.