You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Catalan_language

Context:
In Spain, every person officially has two surnames, one of which is the father's first surname and the other is the mother's first surname. The law contemplates the possibility of joining both surnames with the Catalan conjunction i ("and").

Question:
Which one of one's father's surnames is used?

first