The Computer Fraud and Abuse Act (CFAA) primarily protects against unauthorized access to computer systems and data, as well as fraud and abuse related to those systems. Out of the options provided, the situation that the CFAA would most likely protect against is:
A. a teenager illegally downloading a song
While the act of illegally downloading a song may involve copyright laws more directly, if the download involves unauthorized access to a computer system (e.g., bypassing a security measure to access a music database), it could fall under the CFAA's protections against unauthorized computer access.
However, it’s important to note that the CFAA is often more focused on issues like hacking and unauthorized access to secure systems rather than copyright infringement specifically. The other options listed involve different legal frameworks that are not primarily addressed by the CFAA.