What is the most efficient way an attacker located in remote location to infect this banking Trojan on a victim’s machine?

BankerFox is a Trojan that is designed to steal users’ banking data related to certain banking
entities.
When they access any website of the affected banks through the vulnerable Firefox 3.5 browser,
the Trojan is activated and logs the information entered by the user. All the information entered in
that website will be logged by the Trojan and transmitted to the attacker’s machine using covert
channel.
BankerFox does not spread automatically using its own means. It needs an attacking user’s
intervention in order to reach the affected computer.

What is the most efficient way an attacker located in remote location to infect this banking Trojan
on a victim’s machine?

A.
Physical access – the attacker can simply copy a Trojan horse to a victim’s hard disk infecting
the machine via Firefox add-on extensions

B.
Custom packaging – the attacker can create a custom Trojan horse that mimics the appearance
of a program that is unique to that particular computer

C.
Custom packaging – the attacker can create a custom Trojan horse that mimics the appearance
of a program that is unique to that particular computer

D.
Custom packaging – the attacker can create a custom Trojan horse that mimics the appearance
of a program that is unique to that particular computer

E.
Downloading software from a website? An attacker can offer free software,such as shareware
programs and pirated mp3 files