What is defined as a step-by-step list of rules or instructions for solving a problem?

The correct answer is an algorithm, which is defined as a step-by-step list of rules or instructions for solving a problem. Algorithms are fundamental in the fields of computer science and software development because they provide a clear, logical sequence to process data and perform tasks efficiently.

In this context, an algorithm can be used to outline the necessary steps for coding solutions to specific problems, ensuring clarity and order in the implementation process. This structured approach is crucial when developing software, as it helps programmers break down complex tasks into manageable components.

The other terms, while relevant to the field of software and application development, do not refer to the concept of a step-by-step list for solving problems. An application is a software program designed for end-users, alpha testing pertains to the early testing phase of software development, where it is tested internally, and anti-virus refers to software specifically designed to detect and eliminate malware. Each of these has distinct purposes and definitions that do not encapsulate the structured approach offered by an algorithm.