The correct answer to this question isA Saint whose writings have provided great learning to the Church. The writings that the Doctors of the Church provide are seen to be able to be used in any age of the Church. Both men and women can be Doctors of the Church.
Regardless of their gender, the Doctors of the Church are seen as being extremely knowledgeable about the Church and theology. The Doctors writings are seen to be inspired by the Holy Spirit. Over time, there have been many Doctors of the Church, including St. Hilary of Poitiers and St. Ephraem the Syrian.