Explanation:

The correct option is (A) Programmer. A programmer is an individual who writes, tests, and maintains computer programs. Their primary role involves translating software designs and requirements into executable code using various programming languages. While other roles might also involve writing code, 'programmer' is the most direct and fundamental title for someone performing these core tasks. (B) A Computer scientist typically focuses on the theoretical foundations of information and computation, including algorithm design, data structures, and artificial intelligence, rather than solely writing and testing programs. (C) A Software engineer applies engineering principles to the design, development, maintenance, testing, and evaluation of software. This role is broader than a programmer, often involving architectural design, project management, and quality assurance in addition to coding. (D) A Project developer is a more general term that could refer to someone involved in various aspects of a project's development, not exclusively writing and testing programs. It might encompass roles like project manager, business analyst, or even a software engineer. (E) None of these is incorrect as 'programmer' is the most fitting title.