An intruder attempted malicious activity and exchanged emails with a user and received corporate information, including email distribution lists. The intruder asked the user to engage with a link in an email. When the fink launched, it infected machines and the intruder was able to access the corporate network. Which testing method did the intruder use? 

Answer options:

A. social engineering
B. eavesdropping
C. piggybacking
D. tailgating

A