What tool assists an incident responder in tracking an email and extracting significant investigative information?

The correct answer is Zendio. This tool is designed specifically to assist incident responders in tracking emails and extracting essential investigative information. Its functionality includes detailed analysis of email headers, which can reveal the origin of the email, its route through various mail servers, and any potential malicious indicators contained within the message. This can significantly aid in understanding the context of an incident, identifying the sender, and tracing the email's activity over time.

Other tools mentioned might serve similar functions, but Zendio is particularly noted for its comprehensive analysis capabilities in incident response scenarios. Understanding the specific features and advantages that Zendio offers over its counterparts can enhance an incident responder's ability to effectively manage and investigate potential email threats.