What techniques involve changing the code and media items to improve loading performance of web pages?

The correct choice emphasizes the process of refining web pages to improve their loading performance, which is crucial for user experience and search engine rankings. Website optimization refers specifically to strategies and techniques used to enhance the efficiency of a website, including minimizing the size of images, compressing files, optimizing code, and implementing caching strategies. These adjustments reduce the amount of data that needs to be downloaded, which leads to faster loading times.

Focusing on effective optimization practices not only improves speed but also helps in better resource management and performance across various devices and connections. Such work can involve analyzing website performance metrics, identifying bottlenecks, and applying best practices to ensure that users experience fewer delays when accessing content.

While the other options touch on related concepts, they do not directly capture the essence of improving loading performance as specifically as website optimization does. For instance, web design largely concerns the visual layout and user interface aspects, while web development encompasses the broader creation and maintenance of software, and website enhancement may refer to adding features rather than focusing on performance improvements.