What are step-by-step instructions that guide a computer's operations?

The correct answer is that step-by-step instructions that guide a computer's operations are best described as programs. A program is a set of coded instructions that a computer follows to perform specific tasks. This may include various operations such as calculations, data management, user interactions, and more, all laid out sequentially to ensure the computer executes them in the intended order.

In contrast, while algorithms are also step-by-step procedures, they are more theoretical frameworks for solving problems and can exist without being implemented in code. Protocols refer to rules or standards that define how data is transmitted and communicated over networks but do not specifically describe computer operations. Functions, on the other hand, are smaller, reusable pieces of code within a program that perform a specific task, but they do not encompass the full breadth of operations that a program can execute as a whole.

Thus, it is the comprehensive collection of instructions within a program that ultimately guides a computer's operations.