Which practice in software development ensures that code changes can be merged reliably?

Version control is the practice in software development that ensures code changes can be merged reliably. It allows multiple developers to work on the same codebase simultaneously without the risk of overwriting each other’s changes. By using a version control system, developers can track changes, revert to earlier versions, and manage different branches of the code. This facilitates collaboration and helps maintain a stable and organized codebase, enabling reliable merging of updates and features.

The other options, such as code refactoring, focus on improving the structure and readability of existing code without changing its external behavior, but do not inherently address the merging of changes. Continuous delivery emphasizes the automation of bringing code changes to production, but it also relies on version control for managing changes. Agile development is a methodology that promotes iterative development and teamwork but does not specifically provide the technical means for merging code. Thus, version control is the foundational practice that supports reliable merges in the software development lifecycle.