What has William just installed?

William has received a Chess game from someone in his computer programming class through
email. William does not really know the person who sent the game very well, but decides to install
the game anyway because he really likes Chess.

After William installs the game, he plays it for a couple of hours. The next day, William plays the
Chess game again and notices that his machine has begun to slow down. He brings up his Task
Manager and sees the following programs running:

What has William just installed?

A.
Zombie Zapper (ZoZ)

B.
Remote Access Trojan (RAT)

C.
Bot IRC Tunnel (BIT)

D.
Root Digger (RD)