The correct answer is A. A system in which a computer is used to turn data into information.
A computer-based information system is a system that uses a computer to store, process, and retrieve information. It can be used to manage data, automate tasks, and provide decision support.
Option B, inputting data, is a part of the process of using a computer-based information system. Data is input into the system through a variety of means, such as keyboards, mice, scanners, and cameras.
Option C, processing data, is another part of the process of using a computer-based information system. Data is processed by the computer to produce information. This information can be used in a variety of ways, such as to make decisions, to generate reports, and to track progress.
Option D, performing complex mathematical calculations, is a task that can be performed by a computer-based information system. However, this is not the primary purpose of such a system.
Option E, data is put into the computer for processing, is a statement that is true of all computer-based information systems. However, it does not fully describe the purpose of such a system.
In conclusion, the correct answer is A. A system in which a computer is used to turn data into information.