In the context of Trojans, what is the definition of a Wrapper?

A.
A tool used to encapsulate packets within a new header and footer

B.
An encryption tool to protect the Trojan

C.
A tool used to calculate bandwidth and CPU cycles wasted by the Trojan

D.
A tool used to bind the Trojan with a legitimate file

Explanation:
These wrappers allow an attacker to take any executable back-door program and combine it with any legitimate executable, creating a Trojan horse without writing a single line of new code.