Final answer:
The best solution for protecting high security product designs not accessible by corporate networks or the Internet is an air gap, because it physically isolates the computer or network from other networks, thus preventing network-based attacks or unauthorized access.
Step-by-step explanation:
The best solution to protect very high security product designs that are required to be protected and controlled by government regulations and not accessible by corporate networks or the Internet is A. An air gap. An air gap is a network security measure that involves physically isolating a computer or network from other networks, such as the internet or corporate networks. This ensures that the designs remain secure and cannot be accessed or compromised through network-based attacks.
While a Faraday cage can protect electronic devices from external electrical fields and charges, it does not prevent network-based attacks or unauthorized access to data stored on devices within it. Similarly, a shielded cable would protect against interference for data in transit, but that alone does not secure the data at rest. A demilitarized zone (DMZ) is a network area that serves as a buffer between a protected or private network and an untrusted network, like the internet, but does not offer the complete isolation provided by an air gap.