According to the Scrum Guide, the best approach for Scrum Teams in order to produce valuable Increments is to have each Developer work on the component where they feel that they can contribute. This means that the Developers can self-organize and collaborate effectively to deliver a valuable Increment that meets the Definition of Done and the Sprint Goal. The other options are not valid approaches, as they either imply that the Developers work in silos or rely on external people (such as developing functionality from beginning to end, working on an independent set of components, or working only as an independent layer of the system).