Which of the following is an example of an IT system?

The correct answer is database systems because they are designed specifically to store, manage, and retrieve data using software applications. These systems allow for the efficient organization and manipulation of data, which is a fundamental function of information technology in various sectors. In the context of IT systems, database systems play a crucial role by providing the necessary infrastructure for applications to operate on data, supporting everything from transaction processing to data analysis.

The other options, while they may involve technology, are more closely related to physical infrastructure rather than information technology systems. Fuel and pump stations, water distribution, and electricity generation involve operational systems that provide essential services but do not primarily function as IT systems. They may utilize information technology in managing their operations (e.g., monitoring systems, or control networks), but they are not, in themselves, categorized as IT systems.