What key action is involved in replying to a comment in a spreadsheet cell?

The key action involved in replying to a comment in a spreadsheet cell is clicking the Post button to submit the comment. When working within a spreadsheet environment, particularly those that support collaborative features such as Google Sheets or Microsoft Excel, users often have the capability to respond to comments left by others. After entering a response to a comment, using the Post button is essential for formalizing and conveying that reply so that it is recorded and visible to all users who are accessing the spreadsheet.

This process ensures that communication is clear and organized, maintaining a structured dialogue about the content of the spreadsheet. Clicking the Post button not only submits the reply but also typically updates the comment thread, allowing participants to track the dialogue's progression easily.

The other choices may involve various actions related to comments, but they do not specifically encompass the definitive act of submitting a reply within the context of responding to a comment.