Which of the following represents an action to stop debate on a topic?

The action that represents stopping debate on a topic is known as "calling the question." This motion is typically used in parliamentary procedure to bring the discussion to a close and move directly to a vote on the matter currently under consideration.

When this action is taken, it indicates that a member believes enough debate has occurred and that it is time to decide the issue at hand. This usage helps to maintain order in meetings and ensures that discussions do not drag on indefinitely. In the context of the choices provided, it accurately reflects an action focused on concluding discourse.

The other options serve different purposes in parliamentary procedure: amending is about modifying a motion, division of assembly pertains to verifying a vote, and parliamentary inquiry allows members to ask questions regarding procedural matters. Each has its key role but does not serve the primary function of halting debate.