A step-by-step procedure used to solve a problem is called

Operating system
Algorithm
Application program
All of the above E. None of the above

The correct answer is B. Algorithm.

An algorithm is a step-by-step procedure used to solve a problem. It is a finite sequence of instructions that are well-defined and can be executed in a finite amount of time. Algorithms are used in a variety of fields, including computer science, mathematics, and engineering.

An operating system is a software program that manages the computer’s hardware and software resources and provides a platform for running application programs. Application programs are computer programs that are designed to perform a specific task, such as word processing, spreadsheet management, or web browsing.

Therefore, the correct answer is B. Algorithm.