Right answer: programador
Computing (also called IT) is responsible for managing methods, techniques and processes in order to store, process and transmit information and data in digital format.
This branch has several areas of application, among which are: business management, information storage, process control, communications, medicine; among others. In addition, it covers the main foundations of computer science, such as programming for software development, the architecture of computers and hardware, networks and artificial intelligence. It even applies to various topics of electronics.
Therefore, a person working in that branch must be a programmer (programador).
The complete sentence is:
Mi rama de estudio es informática. Soy programador
My branch of study is computer science. I’m a programmer
The options peluquero (barber), policía (police) and pintor (painter) are incorrect because are not related with the computer science profile.