Choose the only correct sentence, as far as the use of the indefinite articles is concerned.
Antonio is studying Economic Sciences at a university in Rio de Janeiro.
Antonio used to wear an uniform when he was a pupil in a rural public school in Colinas.
He would like to study in an European school when he finishes his university course.
English is an universal language because it is spoken in different countries worldwide.
Antonio has never been to a underground shopping center.