Comprehensive and Detailed Explanation From Exact Extract:

In Agile software development, the process is iterative, and writing code to create a version of the program occurs during the implementation phase. According to foundational programming principles and Agile methodologies (e.g., Certiport Scripting and Programming Foundations Study Guide, Agile Manifesto), implementation involves coding the software based on requirements and design.

Agile Phases Overview:

Analysis: Gathers and refines requirements (e.g., customer needs as user stories).

Design: Plans the technical solution (e.g., defining functions, classes, or architecture).

Implementation: Writes and integrates code to create a working version.

Testing: Verifies the code meets requirements.

Option A: "Implementation." This is correct. Starting to write the first version of the program involves coding, which is the core activity of the implementation phase. For example, the programmer might write functions or classes to meet customer requirements.

Option B: "Testing." This is incorrect. Testing occurs after coding to verify the program’s functionality, not during the writing of the first version.

Option C: "Design." This is incorrect. Design involves planning the program’s structure (e.g., specifying functions or objects), not writing the code.

Option D: "Analysis." This is incorrect. Analysis involves receiving and refining requirements, which the programmer has already done before starting to code.

Certiport Scripting and Programming Foundations Study Guide (Section on Agile Implementation).

Agile Manifesto: “Working Software” (http://agilemanifesto.org/).

Sommerville, I., Software Engineering, 10th Edition (Chapter 4: Agile Software Development).