A botnet is

A) a huge number of hijacked Internet computers that have been set up to forward traffic, including spam and viruses, to other computers on the Internet.
B) a piece of software code that inserts itself into a host or operating system to launch DOS attacks.
C) a piece of code in a worm that spreads rapidly and exploits some known vulnerability.
D) a production system that looks like it does real work, but that acts as a decoy and is watched to study how network intrusions occur.

A