In web development, pseudo-elements are used in CSS (Cascading Style Sheets) to style specific parts of an element. They are specified using double colons (::) followed by the name of the pseudo-element. The valid pseudo-elements in CSS include:
::before - This pseudo-element inserts content before an element's content.
::after - This pseudo-element inserts content after an element's content.
The question asks which of the options is not a valid pseudo-content element:
before
after
selection
selected
The valid pseudo-elements used in CSS are ::before and ::after. However, CSS does not recognize 'selection' or 'selected' as valid pseudo-content elements.
::selection is a pseudo-element that styles the portion of a document that is selected by the user (like when you highlight text).
:selected is not a valid CSS pseudo-element.
Therefore, among the options provided, 'selected' is not a valid pseudo-content element, making it the correct choice for the answer.