What are programs or instructions that tell a computer how to perform tasks called?

The correct answer is software applications. Software applications are programs designed to help users perform specific tasks on a computer or other devices. These applications act as tools that enable users to accomplish a wide array of functions, such as word processing, data management, graphic design, and communication. Essentially, they provide the interface through which users can interact with the underlying technology to achieve their goals.

In this context, algorithms refer to a set of procedures or formulas for solving problems, serving as the backbone of how software applications operate but not encapsulating the complete definition of software itself. Data sets represent collections of data used within software but do not entail the instructions or programs that execute tasks. Operating systems are a type of software that manage hardware resources and facilitate the running of software applications, but they are not synonymous with all programs or instructions that tell a computer how to perform tasks. Therefore, software applications indeed is the most appropriate term for describing programs that tell a computer how to execute various tasks.