The correct answer is A. User.
A user is someone who uses a computer to perform tasks such as browsing the internet, checking email, or playing games. They may have some basic knowledge of how to use a computer, but they are not typically required to have any technical knowledge.
A computer operator is someone who is responsible for the day-to-day operation of a computer system. They may be responsible for tasks such as loading and unloading data, running programs, and monitoring the system for errors. They typically have some basic technical knowledge, but they are not typically required to have a deep understanding of computer systems.
A system analyst is someone who is responsible for designing and developing computer systems. They typically have a deep understanding of computer systems and how they work. They are responsible for identifying the needs of the users and designing a system that meets those needs.
A programmer is someone who writes code to create computer programs. They typically have a deep understanding of computer programming languages and how they work. They are responsible for writing the code that tells the computer what to do.
A computer professional is someone who has a deep understanding of computer systems and how they work. They may be involved in any aspect of the development, use, or maintenance of computer systems. They typically have a degree in computer science or a related field.
In conclusion, the user is the person who probably has the least amount of technical knowledge.