When the developer uses <data-sly-call="${clientlib.css @ categories='library.one'}"/>, it will include the CSS files for 'library.one' and its dependencies. 'library.one' has dependencies 'library.three' and 'library.four', which means their CSS files will also be included. The order in which libraries are included is based on their dependencies. Hence, 'library.four' (being a dependency of 'library.three') will be included first, then 'library.three', and finally 'library.one'. Therefore, the resulting HTML will be: <link rel="stylesheet" href="/library.four.css"/><link rel="stylesheet" href="/library.three.css"/><link rel="stylesheet" href="/library.one.css"/>. So, the correct answer is C.