Task: Question Answering
Input (English): Passage: In the Low Middle Ages, Catalan went through a golden age, reaching a peak of maturity and cultural richness. Examples include the work of Majorcan polymath Ramon Llull (1232–1315), the Four Great Chronicles (13th–14th centuries), and the Valencian school of poetry culminating in Ausiàs March (1397–1459). By the 15th century, the city of Valencia had become the sociocultural center of the Crown of Aragon, and Catalan was present all over the Mediterranean world. During this period, the Royal Chancery propagated a highly standardized language. Catalan was widely used as an official language in Sicily until the 15th century, and in Sardinia until the 17th. During this period, the language was what Costa Carreras terms "one of the 'great languages' of medieval Europe". Question: What was the official language of Sicily until the 15th century?
Output (English): Catalan