Which tool is appropriate for sending an autoresponder email to prospects who request a download?

The appropriate tool for sending an autoresponder email to prospects who request a download is a completion action. Completion actions are automated tasks that can be triggered based on specific actions taken by a prospect. When a prospect fills out a form to request a download, a completion action can be utilized to automatically send a predefined autoresponder email to acknowledge the request or deliver the content. This process enhances the prospect's experience by providing immediate feedback or content related to their interest.

In contrast, segmentation rules are used to sort and group leads based on particular criteria, but they do not directly facilitate the sending of automatic responses. Dynamic lists are typically employed for creating lists of contacts that change dynamically based on specified criteria, rather than sending immediate follow-up communications. Lastly, while automation rules also orchestrate communication flows, they are generally broader and may involve multiple actions or conditions that extend beyond the single task of sending an autoresponder email upon a specific action like a download request. Therefore, for the specific function of sending an email in response to a download request, the completion action is the most suitable choice.