What is an example of the way in which a Trojan horse commonly spreads to other computers?

A.
It inserts copies of itself into other computer programs

B.
It traverses a network by exploiting a vulnerability

C.
It pretends to be a document from a friend

D.
It downloads from an infected web page

Explanation:
Trojan horses are commonly found on websites that offer free software, such as shareware
programs. These communal gathering spots on the Web give Trojan horse writers a degree of
anonymity along with the chance of attacking as many random victims as possible. Since website
operators rarely have time to thoroughly examine every file posted, an occasional Trojan horse can
slip through the checking procedures unnoticed. –
Reference: HOW TROJAN HORSES SPREAD
http://etutorials.org/Misc/computer+book/Part+2+Dangerous+Threats+on+the+Internet/Chapter+8
+Trojan+Horses-+Beware+of+Geeks+Bearing+Gifts/HOW+TROJAN+HORSES+SPREAD/