What is the correct answer and explanation?

The correct answer is a) Jan Žižka (Ян Жижка). He was indeed the leader of the Hussite wars in Bohemia. Explanation for the other options: * Clovis was a Frankish king from the Merovingian dynasty. * Urban II was a Pope known for initiating the First Crusade. * Johann Gutenberg was the inventor of printing.