Which CSS positioning scheme should a developer use to ensure that an element remains in the same position when a user scrolls a page?

Static positioning is the default CSS positioning scheme in which elements are positioned according to the normal flow of the document. Elements with static positioning will scroll with the rest of the page, meaning they cannot maintain a fixed position regardless of user scroll actions.

Relative positioning allows an element to be positioned relative to its original position in the normal document flow. While it can be moved using top, right, bottom, or left properties, it still scrolls with the page content and does not maintain a fixed position, rendering it unsuitable for the requirement.

Absolute positioning removes an element from the normal document flow and positions it relative to its nearest positioned ancestor. While it can create a fixed appearance within a certain context, it does not keep the element fixed in the viewport when the user scrolls, which is necessary for the requirement.