Option B (Two-factor authentication) can indeed be an effective Network Access Control (NAC) capability to better protect the network from unauthorized internal access. Two-factor authentication adds an extra layer of security by requiring users to provide two different types of authentication factors, such as a password and a unique code sent to their mobile device, before gaining access to the network.
By implementing two-factor authentication, even if an unauthorized individual gains access to a user's credentials (e.g., username and password), they would still need the second factor (e.g., the code sent to the user's mobile device) to successfully authenticate and gain access to the network. This helps mitigate the risk of unauthorized internal access, even if internal credentials are compromised.
Therefore, both options A (Port security) and B (Two-factor authentication) can be valid choices to increase security and protect the network from unauthorized internal access. The choice between the two would depend on the specific requirements and context of the organization's network environment.