Answer:
a. spoofing
Step-by-step explanation:
In this context, it is clear that John was a victim of spoofing. In information security, spoofing occurs when a person or program identifies itself as another by falsifying data, in order to gain an illegitimate advantage. In this example, the program identified itself as a computer registry cleaner in order to gain access to John's passwords and credit card information. Spoofing can apply to emails, phone calls, websites, IP address, Address Resolution Protocol (ARP), or Domain Name System (DNS) server.