What do Sitecore's Helix design guidelines emphasize?

Sitecore's Helix design guidelines emphasize the separation of concerns and modular architecture as essential principles for building scalable and maintainable applications. This approach encourages developers to create components that are well-defined and encapsulated, allowing for easier debugging, testing, and reuse. By organizing code into clearly defined layers or modules, each with specific responsibilities, developers can enhance collaboration among teams and streamline updates or changes to individual parts of the system without affecting the entire application.

This modular architecture aligns with best practices in software development, promoting maintainable codebases that can evolve over time. It also facilitates agility in development, making it easier to adapt to changing business requirements or integrate new features.

The other options do not align with the Helix guidelines: a monolithic application structure goes against the modular approach; outdated programming techniques are not promoted, as Helix encourages modern practices; and while managing Sitecore items is important, it is not the primary focus of the Helix guidelines, which are more concerned with architectural principles than with item management.