Right answer: Catalan
Catalonia is an autonomous community of Spain, is formed by the provinces of Barcelona (which is its capital), Gerona, Lérida and Tarragona.
In Catalonia the language that identifies it is Catalan, therefore in Barcelona Catalan is spoken in addition to Spanish (Castilian).
It should be noted that Catalan is a Romance language, that is, it comes from the Latin spoken by the ancient Romans. It was also influenced by other languages such as the Ibero-Basque, the Arabic and Germanic languages.