Answer:
B. a Trojan horse
Explanation:
A Trojan Horse is a malware that disguises itself as a legitimate code or software. In this scenario, Shelly downloaded what she thought was an arcade game. When the file is executed, it gives the attacker remote access to the affected computer allowing them to steal and access sensitive information on the user's computer This type of Trojan Horse malware is specifically known as a Remote Access Trojan (RAT).
