What action does a previous question take during a debate?

In parliamentary procedure, a "previous question" is a motion that is used to bring a debate to a close and compel an immediate vote on the matter at hand. This is an important tool to ensure that discussions do not go on indefinitely and that decisions can be made in a timely manner. By invoking the previous question, members signal that they believe sufficient debate has occurred and that it’s time to proceed to a vote. This process helps maintain order and efficiency in deliberative assemblies, allowing for a more streamlined decision-making process.

The other options do not accurately reflect the purpose of a previous question. For example, allowing for extended discussion would directly contradict the intent of the motion, which seeks to curtail debate. Similarly, introducing new topics or postponing discussions are not functions served by a previous question, further affirming that its primary role is to shorten debate and trigger a vote.