What is the mechanism behind Threat Extraction?

What is the mechanism behind Threat Extraction?
A . This a new mechanism which extracts malicious files from a document to use it as a counter-attack against its sender.
B . This is a new mechanism which is able to collect malicious files out of any kind of file types to destroy it prior to sending it to the intended recipient.
C . This is a new mechanism to identify the IP address of the sender of malicious codes and put it into the SAM database (Suspicious Activity Monitoring).
D . Any active contents of a document, such as JavaScripts, macros and links will be removed from the document and forwarded to the intended recipient, which makes this solution very fast.

Answer: D