A piece of malicious code that can replicate itself has no productive purpose and exist only to damage computer systems or create further vulnerabilities is called a?

A.
Logic Bomb

B.
Worm

C.
Trojan Horse

D.
SYN flood

E.
Virus

Explanation:
A virus is a piece of software designed to infect a computer system. The virus may do nothing more than reside on the computer. A virus may also damage the data on your hard disk, destroy your operating system, and possibly spread to other systems.
Reference: Security + (SYBEX) page 76