Which concept in programming focuses on ensuring every function in a code block has a clear purpose?

• A. Promise
• B. Delay
• C. Refactoring
• D. Optimization

Answer: (A)

Refactoring is the practice of restructuring existing code to improve its readability, structure, and maintainability without changing how it behaves. When you refactor, you often break up complex functions into smaller, well-named ones so each function has a single, clear purpose. This makes the code easier to understand, test, and modify later, because you can reason about each piece in isolation and change or extend one piece without unintended side effects elsewhere.

For example, if a function is doing multiple tasks—reading data, transforming it, and saving results—that's a sign to extract those tasks into separate functions with focused responsibilities (readData, transformData, saveResults). The surrounding code then reads more like a clear sequence of steps, and changes to one step won’t ripple unpredictably through the others.

In this context, the other terms aren’t about organizing code around clear, single-purpose functions: a Promise is a mechanism for handling asynchronous values, a delay is about pausing execution, and optimization is about improving performance or resource use. Refactoring targets the structure and clarity of your code so each function has a well-defined role.