Think of a Normally-Functioning Video Game Program That Has a Hiding

Think of a normally-functioning video game program that has a hiding malware. A user can download and install the video game program from a website and enjoy it. But, at the same time, this also result in the secret installation of the malware, creating a hidden backdoor on the victim computer. Then, the malware must be

A) virus
B) spyware
C) ransomware
D) worm
E) Trojan